Start backing away from a fight (4)
I believe the answer is:
bout
'a fight' is the definition.
(as in a bout in boxing)
'start backing away' is the wordplay.
'start' says to take the initial letters.
'away' becomes 'out' (similar in meaning).
The first letter of 'backing' is 'b'.
'b'+'out'='BOUT'
'from' acts as a link.
(Other definitions for bout that I've seen before include "Spell; contest" , "Attack (of illness)" , "Short period of intense activity" , "Contest between boxers" , "Fight; instance of illness" .)