Rep left cup game, tense (10)
I believe the answer is:
pluperfect
'tense' is the definition.
(pluperfect is a kind of tense)
'rep left cup game' is the wordplay.
'game' indicates an anagram (solving anagrams is a game).
'rep'+'left'+'cup'='repleftcup'
'repleftcup' with letters rearranged gives 'PLUPERFECT'.
(Other definitions for pluperfect that I've seen before include "Tense with "had" and past participle" , "Verbal tense" , "(In grammar) a tense - per cup left (anag)" .)