Trumpet cousin (6)
I believe the answer is:
cornet
'trumpet cousin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cornet that I've seen before include "I could provide musical accompaniment" , "Brass instrument - ice cream" , "It's blown" , "Ice-cream - brass instrument" , "Musical instrument like small trumpet" .)