Baby fox, or a first-aid box (3)
I believe the answer is:
kit
This clue is a double definition.
'baby fox' is the first definition.
(I've seen this in another clue)
'a first-aid box' is the second definition.
(I've seen this in another clue)
(Other definitions for kit that I've seen before include "Young stoat" , "In strip" , "Old song 'Pack up your troubles in your old . . . bag'" , "Set - uniform - gear" , "Supplies" .)