Instant food appears after time (5)
I believe the answer is:
trice
'instant' is the definition.
(synonyms)
'food appears after time' is the wordplay.
'food' becomes 'rice' (rice is a kind of food).
'appears after' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'rice' after 't' is 'TRICE'.
(Other definitions for trice that I've seen before include "Very brief moment" , "Old use for three times" , "Next to no time" , "Haul" , "Short time" .)