Terribly keen to put limit on bone (7)
I believe the answer is:
kneecap
'bone' is the definition.
(I know that kneecap is a type of bone)
'terribly keen to put limit' is the wordplay.
'terribly' indicates an anagram.
'to put' says to put letters next to each other.
'limit' becomes 'cap' (capping is a kind of limiting).
'keen' is an anagram of 'knee'.
'knee'+'cap'='KNEECAP'
'on' is the link.
(Other definitions for kneecap that I've seen before include "The informal patella (7)" , "one going on bender?" , "part of joint" , "Joint protection" , "Horribly punish" .)