At home hard university man becomes brutal (7)
I believe the answer is:
inhuman
'brutal' is the definition.
(I've seen this before)
'at home hard university man' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'hard' becomes 'h' (abbreviation used in pencil classifications).
'university' becomes 'u' (abbreviation for university).
'in'+'h'+'u'+'man'='INHUMAN'
'becomes' is the link.
(Other definitions for inhuman that I've seen before include "Savage, brutal" , "Pitiless - barbarous" , "Without compunction" , "diabolical ..." , "Cruel, barbaric" .)