In traditional cartomancy, the Ace of Clubs is the card of marriage. In olden days, marriages were often arranged based on money and prestige. You could lift your social status by marrying your daughter off to noble family, or to a wealthy landowner. In many cultures the girl was expected to bring along a dowry as well, to add to the husband's holdings. Based on the marriage contract she was usually considered to be the property of her new husband.
Today very few marriage are arranged this way in the western world. It is perhaps for this reason that the Ace of Clubs in modern cartomancy has lost the meaning of marriage. These days, most marriages are based on love, and may be better represented by cards in the suit of Hearts.
The Ace of Clubs does retain its meaning as a "binding contract." The primary meanings for this card include important papers, a legal document, and a contract to be signed. With the Ace of Hearts, the Ace of Clubs can denote a contract to buy or sell a home. With the 10 of Clubs, it would show signing papers on a business. With the 2 of Hearts, representing a child, it would show a legal adoption.
The Ace of Clubs also retains the meaning of "property," and it's the card that represents "a building" in Modern Cartomancy. The Ace of Hearts is the home, but the Ace of Clubs can represent anything from a friend's house, to the workplace, to a commercial establishment, to a large institution.
Here are a few fun combinations to consider...
Ace of Clubs + 2 of Hearts = elementary school, nursery school, or dance studio
Ace of Clubs + 3 of Hearts = beauty salon, flower shop
Ace of Clubs + 5 of Hearts = furniture store, clothing store, department store
Ace of Clubs + 4 of Spades = a hospital, or jail
Ace of Clubs + 7 of Spades = a bar (with the 2 of Hearts to show dancing = nightclub)
Ace of Clubs + 8 of Spades = doctor's office, dentists office, medical clinic
Ace of Clubs + King of Spades + any other King = police station, also joining the military
Ace of Clubs + Ace of Diamonds = the post office
Ace of Clubs + 2 of Diamonds = a restaurant
Ace of Clubs + 4 of Diamonds = a bank
Ace of Clubs + 5 of Diamonds = the courthouse, shopping center
Ace of Clubs + King of Diamonds = a college or university
Ace of Clubs + 3 of Clubs = garden center, barbershop
Ace of Clubs + 6 of Clubs = a bookstore, a factory (manufacturing plant)
Ace of Clubs + 7 of Clubs = a shoe store
Ace of Clubs + 8 of Clubs = the building where you work
Ace of Clubs + 9 of Clubs = a passport, but it can also represent a hotel
Ace of Clubs + 4 of Clubs = a car garage
Another way to look at it would be to consider that the Ace of Clubs refers to a service organization, whether it's a retail shop or a large corporation or a staunch institution. In fact, this card can even represent the military. Two Kings falling together would generally indicate a police officer. If the Ace of Clubs is nearby, the combination could refer to a soldier. The combination Any King + King Spades + 4 of Spades would show someone being arrested. The combination Any King + King of Spades + Ace of Clubs would show someone joining the military. If the Ace of Clubs falls first, it would show being conscripted into the military. The King of Spades must appear in the combination to show "duty." Queens in place of the Kings would indicate that it's a female.
The Ace of Clubs can represent a legal will, and it can also represent one's personal power of will. This card shows a personal choice backed by determination. When the Ace of Clubs falls in a reading about someone's intentions, it shows that they have already made up their mind on a course of action, and have no intentions of deviating from their chosen direction. The surrounding cards will usually offer a clue about the choice. If the Ace of Clubs is surrounded by Spades, it can show someone who is weak-willed, and unable to follow-through on their plans.