Young Tom needs gear, camping equipment mostly (6)
I believe the answer is:
kitten
'young tom' is the definition.
(tom is a cat so young tom is a kitten)
'gear camping equipment mostly' is the wordplay.
'gear' becomes 'kit' (kit is a kind of gear**).
'camping equipment' becomes 'tent'.
'mostly' means to remove the last letter.
'tent' with its final letter taken away is 'ten'.
'kit'+'ten'='KITTEN'
'needs' is the link.
(Other definitions for kitten that I've seen before include "Little feline" , "one to become queen?" , "Mini-mog?" , "Little Tom, perhaps" , "Young feline animal" .)