Con-man reported like big cat (7)
I believe the answer is:
cheetah
'big cat' is the definition.
(cheetah is a kind of big cat)
'con-man reported' is the wordplay.
'con man' becomes 'cheater' (I've seen this in another clue).
'reported' shows a homophone (sound like).
'cheater' sounds like 'CHEETAH'.
'like' acts as a link.
(Other definitions for cheetah that I've seen before include "Swift-running cat" , "Swift large wild cat with spotted coat" , "Very fast mammal" , "Fast-moving creature" , "African native" .)