Enamelwork loons, nice for breaking (9)
I believe the answer is:
cloisonne
'enamelwork' is the definition.
(I've seen this before)
'loons nice for breaking' is the wordplay.
'for breaking' is an anagram indicator.
'loons'+'nice'='loonsnice'
'loonsnice' is an anagram of 'CLOISONNE'.
(Other definitions for cloisonne that I've seen before include "Sort of design" , "Panelled enamelwork" , "enamelware" , "Enamel work" .)