Old curiosities in remarkably barbaric boxing clubs (4-1-4)
I believe the answer is:
bric-a-brac
'old curiosities' is the definition.
(I've seen this before)
'remarkably barbaric boxing clubs' is the wordplay.
'remarkably' indicates an anagram (I've seen this in other clues).
'boxing' means one lot of letters goes inside another ('box' can mean contain, as in to put in a box).
'clubs' becomes 'c' (abbreviation used in card games such as bridge).
'barbaric' anagrammed gives 'briabrac'.
'briabrac' enclosing 'c' is 'BRIC-A-BRAC'.
'in' acts as a link.
(Other definitions for bric-a-brac that I've seen before include "Knick-knacks" , "Miscellaneous small objects, especially curios" , "Motley collection" , "Miscellaneous small ornaments" , "Odd items of furniture, ornaments etc" .)