Relative better as an abbess (6,8)
I believe the answer is:
mother superior
'abbess' is the definition.
(synonyms)
'relative better as' is the wordplay.
'relative' becomes 'mother' (mother is a kind of relative).
'better as' becomes 'superior' (I've seen this before. I am not sure about the 'as' bit.).
'mother'+'superior'='MOTHER SUPERIOR'
'an' is the link.
Can you help me to learn more?
(Other definitions for mother superior that I've seen before include "head of religious community" , "First among sisters" , "leading nun" , "leader of religious community" .)