Aspic cooked with pepper (8)
I believe the answer is:
capsicum
'pepper' is the definition.
('capsicum' can be a synonym of 'pepper')
'aspic cooked with' is the wordplay.
'cooked' indicates anagramming the letters.
'with' becomes 'cum' (I've seen this in other clues).
'aspic' anagrammed gives 'capsi'.
'capsi'+'cum'='CAPSICUM'
(Other definitions for capsicum that I've seen before include "hot stuff perhaps" , "Tropical plant producing peppers -- music cap (anag)" , "Sweet or chilli pepper" , "seeds" , "something pungent" .)