In comic, a cheat's hidden store (5)
I believe the answer is:
cache
'hidden store' is the definition.
(I've seen this before)
'in comic a cheat's' is the wordplay.
'in' indicates a hidden word.
'CACHE' is hidden in the letters of 'comic a cheats'.
(Other definitions for cache that I've seen before include "Reserve" , "Conceal" , "Nest egg" , "Hiding-place for treasure etc" , "(Place in) hidden store" .)