Resistance interrupting attempt to sell fish (5)
I believe the answer is:
trout
'fish' is the definition.
(I know that trout is a fish)
'resistance interrupting attempt to sell' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'interrupting' indicates putting letters inside.
'attempt to sell' becomes 'tout' (I've seen this before).
'r' put into 'tout' is 'TROUT'.
(Other definitions for trout that I've seen before include "Oily fish" , "Game fish related to salmon" , "Rainbow, say" , "Mistiness" , "Fish (associated with Schubert?)" .)