Unbecoming in most of battle: a sharp punch (5,3)
I believe the answer is:
infra dig
'unbecoming' is the definition.
(I've seen this before)
'in most of battle a sharp punch' is the wordplay.
'most of' means to remove the last letter.
'battle' becomes 'fray' (fray is a kind of battle).
'a sharp punch' becomes 'dig' (I can't explain this - if you can you should believe this answer much more).
'fray' with its final letter taken off is 'fra'.
'in'+'fra'+'dig'='INFRA-DIG'
Can you help me to learn more?
(Other definitions for infra dig that I've seen before include "Rigid fan may be lacking in dignity" , "Such as one would not stoop to" , "Unworthy" , "Unbecoming, if daring criminal" , "Beneath one" .)