Tries to collect quantity of food (not peppers, initially) for reptiles (7)
I believe the answer is:
geckoes
'for reptiles' is the definition.
(gecko is a kind of reptile)
'tries to collect quantity of food' is the wordplay.
'tries' becomes 'goes' (go is a kind of try).
'to collect' indicates putting letters inside (inserted letters are collected by others).
'quantity' becomes 'e' (e is a kind of quantity).
'of food' becomes 'ck' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'e'+'ck'='eck'
'goes' placed around 'eck' is 'GECKOES'.
'not peppers initially' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for geckoes that I've seen before include "Vocal lizards with adhesive pads for climbing" , "Central American natives" , "Small lizards" , "Nocturnal lizards" .)