Curtail a card game (7)
I believe the answer is:
abridge
'curtail' is the definition.
(I've seen this before)
'a card game' is the wordplay.
'card game' becomes 'bridge' (bridge is a kind of card game).
'a'+'bridge'='ABRIDGE'
(Other definitions for abridge that I've seen before include "Make short work" , "Tighten up" , "Shorten by using fewer words" , "Make a precis of" , "Big read (anag) - shorten text" .)