One spotted punching peaceful group and small boxers? (6)
I believe the answer is:
undies
'boxers?' is the definition.
(British slang for underwear)
'one spotted punching peaceful group and small' is the wordplay.
'one spotted' becomes 'die' (as in spotted dice used in games).
'punching' means one lot of letters goes inside another (some letters punch a hole in others).
'peaceful group' becomes 'UN' (United Nations - peacekeeping organisation).
'and' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'un'+'s'='uns'
'die' going into 'uns' is 'UNDIES'.
(Other definitions for undies that I've seen before include "linen" , "Undergarments (colloq.)" , "Lingerie -- is nude (anag)" , "clothing not normally seen" , "Used in (anag) -- unmentionables" .)