Chump expected to seize power (4)
I believe the answer is:
dupe
'chump' is the definition.
(thesaurus)
'expected to seize power' is the wordplay.
'expected' becomes 'due' (I've seen this before).
'to seize' means one lot of letters goes inside another.
'power' becomes 'p'.
'due' enclosing 'p' is 'DUPE'.
(Other definitions for dupe that I've seen before include "One deceived, tricked" , "A pawn or patsy" , "Put one over on, cod" , "Cheat" , "Pawn, mug" .)