Small animal with broken leg in mine (6)
I believe the answer is:
piglet
'small animal' is the definition.
(I know that piglet is a type of young mammal)
'broken leg in mine' is the wordplay.
'broken' indicates an anagram.
'in' indicates putting letters inside.
'mine' becomes 'pit' (as in a mining pit).
'leg' is an anagram of 'gle'.
'gle' going into 'pit' is 'PIGLET'.
'with' is the link.
(Other definitions for piglet that I've seen before include "One with home in Hundred Acre Wood" , "Young porker" , "Friend of Pooh" , "Young farm animal" , "One of Christopher Robin's animals" .)