Trick expected to take in chump finally (4)
I believe the answer is:
dupe
'trick' is the definition.
(thesaurus)
'expected to take in chump finally' is the wordplay.
'expected' becomes 'due' (I've seen this before).
'to take in' indicates putting letters inside.
'finally' indicates one should take the final letters.
The final letter of 'chump' is 'p'.
'due' enclosing 'p' is 'DUPE'.
(Other definitions for dupe that I've seen before include "Victim of deceit or fraud" , "Con" , "Swindle" , "Deceive, make fool of" , "Cat's paw" .)