Sell fruit cocktail (4)
I believe the answer is:
hawk
'sell' is the definition.
(hawking is a kind of selling)
'fruit cocktail' is the wordplay.
'fruit' becomes 'haw' (I've seen this before).
'cocktail' becomes 'K' (the end letter or tail of the word 'cocktail').
'haw'+'k'='HAWK'
(Other definitions for hawk that I've seen before include "Sell (goods) on the street" , "Bird - warmonger" , "Raptor - jingoist" , "Clear throat; bird; board to carry mortar" , "Offer (goods) for sale in the street" .)