Aimlessly toy with instrument (6)
I believe the answer is:
fiddle
This might be a double definition.
'aimlessly toy' is the first definition.
'fiddle' can be an answer for 'toy' (synonyms). I'm unsure of the 'aimlessly' bit.
'instrument' is the second definition.
(I know that Fiddle is a instrument)
'with' is the link.
Can you help me to learn more?
(Other definitions for fiddle that I've seen before include "Swindle with informal violin" , "do crookedly with books" , "Commit fraud; instrument" , "Bowed stringed instrument" , "Scam - musical instrument" .)