Man gets General back up, being polite (7)
I believe the answer is:
genteel
'polite' is the definition.
(synonyms)
'man gets general back up' is the wordplay.
'man' becomes 'gent' (gent is a kind of man).
'gets' says to put letters next to each other.
'general' becomes 'lee' (Robert E. Lee - US revolutionary commander).
'back up' says the letters should be written backwards (I've seen 'backing up' mean this).
'lee' in reverse letter order is 'eel'.
'gent'+'eel'='GENTEEL'
'being' is the link.
(Other definitions for genteel that I've seen before include "Overly polite or refined" , "Terribly polite" , "Suited to polite society" , "Artificially polite" , "Marked by refinement in taste and manners" .)