So, it's different for a man (4)
I believe the answer is:
otis
'a man' is the definition.
'so it's different' is the wordplay.
'different' is an anagram indicator (letters placed in a different order).
'so'+'it'='soit'
'soit' is an anagram of 'OTIS'.
'for' acts as a link.
(Other definitions for otis that I've seen before include "Lift man" , "US inventor" , "---- Redding, 1941-67, soul singer" , "Cole Porter's miss who was "unable to lunch today"" , "Miss -- Regrets, Cole Porter song" .)