Doubt about chopped ice in packs for boxing (10)
I believe the answer is:
fisticuffs
'boxing' is the definition.
('fisticuffs' can be a synonym of 'boxing')
'doubt about chopped ice in packs' is the wordplay.
'doubt' becomes 'if' (as in 'it's a big if').
'about' is a reversal indicator.
'chopped' means to remove the last letter.
'in' means one lot of letters goes inside another.
'packs' becomes 'stuffs' (**).
'if' reversed gives 'fi'.
'ice' with its last letter removed is 'ic'.
'ic' inserted within 'stuffs' is 'sticuffs'.
'fi'+'sticuffs'='FISTICUFFS'
'for' is the link.
(Other definitions for fisticuffs that I've seen before include "Scrap" , "Bare-knuckled fighting" , "Pugilism" , "Hand-to-hand combat?" , "Bare-knuckle combat" .)