Man expected around start of day (4)
I believe the answer is:
dude
'man' is the definition.
(I know that dude is a type of man)
'expected around start of day' is the wordplay.
'expected' becomes 'due' (similar in meaning).
'around' is an insertion indicator.
'start of' suggests taking the first letters.
The initial letter of 'day' is 'd'.
'due' enclosing 'd' is 'DUDE'.
(Other definitions for dude that I've seen before include "A (dandy) American city dweller" , "Dandy - city dweller holidaying on ranch" , "City slicker" , "Level" , "US geezer" .)