Dwarf throwing? It'll impress Knut! (15)
I believe the answer is:
rumpelstiltskin
'dwarf' is the definition.
(fairy tale character)
'throwing? it'll impress knut' is the wordplay.
'throwing?' indicates anagramming the letters (I've seen 'thrown' mean this).
'itll'+'impress'+'knut'='itllimpressknut'
'itllimpressknut' anagrammed gives 'RUMPELSTILTSKIN'.
(Other definitions for rumpelstiltskin that I've seen before include "wee chap" , "Fairytale character (Grimm)" , "Character from fairy tale" , "mischievous rascal" , "[FAIRY STORY REF]" .)