Toy instrument (6)
I believe the answer is:
fiddle
This clue is a double definition.
'toy' is the first definition.
('fiddle' can be a synonym of 'toy')
'instrument' is the second definition.
(fiddle is a kind of instrument)
(Other definitions for fiddle that I've seen before include "Awkward task" , "Deception" , "(Play) a violin" , "do crookedly with books" , "Kit perhaps" .)