Mother carries headgear for sage (7)
I believe the answer is:
mahatma
'sage' is the definition.
('mahatma' can be a synonym of 'sage')
'mother carries headgear' is the wordplay.
'mother' becomes 'mama' (mama is a kind of mother**).
'carries' means one lot of letters goes inside another.
'headgear' becomes 'hat' (hat is a kind of headgear).
'mama' going around 'hat' is 'MAHATMA'.
'for' is the link.
(Other definitions for mahatma that I've seen before include "Gandhi, for example" , "(Indian) holy person or sage" , "In India, a title of respect as for Gandhi" , "Holy person or sage in South Asia" , "Savant" .)