God, Norse, shows spine (5)
I believe the answer is:
thorn
'spine' is the definition.
(synonyms)
'god norse' is the wordplay.
'god' becomes 'thor' (Norse god of thunder).
'norse' becomes 'N' (abbreviation in linguistics).
'thor'+'n'='THORN'
'shows' is the link.
(Other definitions for thorn that I've seen before include "North (anag) -- point" , "prickly type" , "A vegetable spike" , "problematic point" , "eg Prickle on rose" .)