Uncompromising student once having say about home (9)
I believe the answer is:
obstinate
'uncompromising' is the definition.
(thesaurus)
'student once having say about home' is the wordplay.
'student once' becomes 'ob' (Old Boy can mean a graduate of a private school).
'having' is a charade indicator (letters next to each other).
'say' becomes 'state' (synonyms).
'about' means one lot of letters goes inside another.
'home' becomes 'in' ('he's home' can mean 'he's in').
'state' placed around 'in' is 'stinate'.
'ob'+'stinate'='OBSTINATE'
(Other definitions for obstinate that I've seen before include "Mulish" , "Inflexible" , "Female bird" , "Cussed" , "Stubbornly persistent" .)