A mother, Conservative, passionate (7)
I believe the answer is:
amatory
'passionate' is the definition.
(I've seen this before)
'a mother conservative' is the wordplay.
'mother' becomes 'ma' (Ma is another word for mother or mum).
'conservative' becomes 'tory' (informal term for a Conservative Party member).
'a'+'ma'+'tory'='AMATORY'
(Other definitions for amatory that I've seen before include "Passionate" , "Loving" , "relating to sexual desire?" , "declaration of love" .)