A fellow lives with a handsome chap (6)
I believe the answer is:
adonis
'handsome chap' is the definition.
(I've seen this before)
'a fellow lives with a' is the wordplay.
'a fellow' becomes 'don' (both can mean an academic).
'lives' becomes 'is' ('be' can be a synonym of 'live').
'with' is a charade indicator (letters next to each other).
'don'+'is'='donis'
'donis' put after 'a' is 'ADONIS'.
(Other definitions for adonis that I've seen before include "extremely handsome chap" , "Handsome young man (of Greek myth)" , "dandy" , "Aphrodite's beloved" , "A very good-looking ancient Greek" .)