Corrupt power ending struggle (4)
I believe the answer is:
warp
'corrupt' is the definition.
(thesaurus)
'power ending struggle' is the wordplay.
'power' becomes 'p'.
'ending' says to put letters next to each other.
'struggle' becomes 'war' (warring is a kind of struggling).
'p' put after 'war' is 'WARP'.
(Other definitions for warp that I've seen before include "Go out of shape" , "Abnormality in character" , "Become bent like timber through heat" , "Distort, twist" , "Make or become out of shape" .)