Two XVs in need of a drink with seconds to go (6)
I believe the answer is:
thirty
'two xvs' is the definition.
(XV is fifteen in Roman numerals)
I don't understand how the remainder of the clue works.
(Other definitions for thirty that I've seen before include "Number of across clues in this puzzle" , "The number of silver coins for betrayal" , "Score and a half" , "Six times five" , "Days in September, April, June and November" .)