Food in packet firm and fresh (5)
I believe the answer is:
crisp
This clue is a triple definition!
'food in packet' is the first definition.
(I've seen this before)
'firm' is the second definition.
(synonyms)
'and' acts as a link.
'fresh' is the third definition.
(similar in meaning)
(Other definitions for crisp that I've seen before include "Fresh and bracing" , "Firm ,dry, brittle" , "Salted 'n' vinegared item?" , "Snappy" , "Snack item" .)