Curse desperate character overcoming resistance (4)
I believe the answer is:
darn
'curse' is the definition.
(I've seen this before)
'desperate character overcoming resistance' is the wordplay.
'desperate character' becomes 'dan' (Desperate Dan the comic character).
'overcoming' means one lot of letters goes inside another.
'resistance' becomes 'r' (abbreviation in physics and electronics).
'dan' placed around 'r' is 'DARN'.
(Other definitions for darn that I've seen before include "Sew" , "curse" , "Mend woollen items" , "Mend (knitted material)" , "Mend with a needle" .)