Born in crowd, raised in Belfast threesome (7)
I believe the answer is:
kneecap
'belfast threesome' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'born in crowd raised' is the wordplay.
'born' becomes 'nee' ('nee' is 'born' in French).
'in' means one lot of letters goes inside another.
'crowd' becomes 'pack' (packing is a kind of crowding).
'raised' says the letters should be written backwards (going up in a down clue).
'pack' written backwards gives 'kcap'.
'nee' placed within 'kcap' is 'KNEECAP'.
'in' is the link.
Can you help me to learn more?
(Other definitions for kneecap that I've seen before include "one going on bender?" , "Joint protection" , "Bone" , "The informal patella (7)" , "part of joint" .)