Hippies eat food (3)
I believe the answer is:
pie
'food' is the definition.
(I know that pie is a type of convenience food)
'hippies eat' is the wordplay.
'eat' says the answer is hidden in the clue (I've seen 'eating' mean this).
'PIE' can be found hidden inside 'hippies'.
(Other definitions for pie that I've seen before include "Type of chart" , "Confused, mixed type" , "Crusty dish" , "where blackbirds sang" , "something with custard, say" .)