He has to live, a man with no master (3)
I believe the answer is:
ben
'he' is the definition.
(I've seen this in another clue)
'live a man with no master' is the wordplay.
'live' becomes 'be' (synonyms).
'with no' indicates named letters should be taken away.
'master' becomes 'ma' (Master of Arts).
'man' with 'ma' taken out is 'n'.
'be'+'n'='BEN'
'has to' acts as a link.
(Other definitions for ben that I've seen before include "Second part of 11" , "A Scottish mountain like Nevis" , "Big . . . is a famous London clock-tower" , "A Gaelic mountain like Bulben" , "High mountain in Scotland" .)