Brand new dart-maker (9)
I believe the answer is:
trademark
'brand' is the definition.
(I've seen this before)
'new dart-maker' is the wordplay.
'new' is an anagram indicator.
'dart'+'maker'='dartmaker'
'dartmaker' anagrammed gives 'TRADEMARK'.
(Other definitions for trademark that I've seen before include "Brand - identifying symbol" , "distinctive characteristic" , "typical" , "Proprietary name" , "sign of concern" .)