Turned card in playing (6)
I believe the answer is:
rancid
'turned' is the definition.
(I've seen this before)
'card in playing' is the wordplay.
'playing' is an anagram indicator.
'card'+'in'='cardin'
'cardin' anagrammed gives 'RANCID'.
(Other definitions for rancid that I've seen before include "Sour like stale grease 96)" , "Stale, rank" , "Turned - foul-smelling" , "Smelling or tasting bad" , "(Of butter) stale" .)