Longman Dictionary of Contemporary English
cash bar
noun
EXAMPLES FROM CORPUS
▪ A cash bar, dancing with country & western band Rimfire, and champagne for $ 15 per couple cover charge.
Wiktionary
cash bar
n. (context US English) A bar at a social event for which guests are required to pay for the drinks themselves. It is opposed to an open bar, where drinks are paid for by the host.
WordNet
cash bar
n. a counter at a large party where you can purchase drinks by the glass
Usage examples of "cash bar".
The dance was an AFL-CIO affair with a polka band and an acre of sheet cake and Jell-O molds, a cash bar, and balloons on the ceilings.
Since nobody had had a chance to spend any money, the Blood Lords and a good number of the techs descended on the cash bar and drank it out half way through the evening.
It was as though a drunk had come to the cash bar at a social function.