Bet about top soldier shortly becoming sharp (7)
I believe the answer is:
pungent
'sharp' is the definition.
(I've seen this before)
'bet about top soldier shortly' is the wordplay.
'bet' becomes 'punt' (punting is a kind of betting).
'about' indicates putting letters inside.
'top soldier shortly' becomes 'gen' (short for general; 'shortly' indicates an abbreviation).
'punt' going around 'gen' is 'PUNGENT'.
'becoming' is the link.
(Other definitions for pungent that I've seen before include "delivering powerful smack" , "Acrid to smell" , "Biting" , "Strong and sharp" , "Smelly" .)