Masters receiving mortarboard for one sage (7)
I believe the answer is:
mahatma
'sage' is the definition.
(term for a wise Hindu leader)
'masters receiving mortarboard for one' is the wordplay.
'masters' becomes 'mm' (an abbreviation for master written twice).
'receiving' indicates putting letters inside.
'mortarboard for' becomes 'ahat' (I can't justify this - if you can you should give a lot more credence to this answer).
'one' becomes 'a' (a thing is one thing).
'mm' going around 'ahat' is 'mahatm'.
'mahatm'+'a'='MAHATMA'
Can you help me to learn more?
(Other definitions for mahatma that I've seen before include "venerable soul" , "In India, a title of respect as for Gandhi" , "Gandhi, for example" , "Wise fellow" , "Hindu leader" .)