Goddess not totally passionate, cold inside (6)
I believe the answer is:
hecate
'goddess' is the definition.
(I've seen this before)
'not totally passionate cold inside' is the wordplay.
'not totally' means to remove the last letter.
'passionate' becomes 'heated' (similar in meaning).
'cold' becomes 'c' (eg on taps).
'inside' is an insertion indicator.
'heated' with its last letter removed is 'heate'.
'heate' enclosing 'c' is 'HECATE'.
(Other definitions for hecate that I've seen before include "Greek goddess of the Underworld" , "Greek goddess associated with witchcraft and the ghost world" , "Divine witch" , "underworld figure" , "Ancient goddess found in the ace" .)