Man's blue background (7)
I believe the answer is:
history
'background' is the definition.
(I've seen this before)
'man's blue' is the wordplay.
'man' becomes 'his' (I've seen this in other clues).
'blue' becomes 'tory' (I've seen this before).
'his'+'tory'='HISTORY'
(Other definitions for history that I've seen before include "eventful past" , "Old record" , "Background" , "Time passed" , "Life story" .)