Point of a thorn, possibly (5)
I believe the answer is:
'point' is the definition.
(north is a kind of point)
'a thorn possibly?' is the wordplay.
'possibly?' is an anagram indicator (I've seen 'possibly' mean this).
'thorn' is an anagram of 'NORTH'.
'of' is the link.
(Other definitions for north that I've seen before include "One looking for contract" , "One of four bridge players" , "Prime Minister" , "who has to follow West's lead?" , "Former PM" .)