Dishonesty in playing an instrument (8)
I believe the answer is:
fiddling
'playing an instrument' is the definition.
'fiddling' can be an answer for 'playing' ('fiddle' can be a synonym of 'play'). I'm not certain of the 'an instrument' bit.
'dishonesty in' is the wordplay.
I cannot really see how this works, but
'in' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for fiddling that I've seen before include "What Nero was doing while Rome burned" , "Tinkering - trifling" , "Such swindles may be" , "wasting time?" , "Cooking the books" .)