Cheating, as bluegrass musician might be? (2,3,6)
I believe the answer is:
on the fiddle
'cheating' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for on the fiddle that I've seen before include "Engaged in cheating" , "Dishonest" , "Cheating (colloq.)" , "leader of the orchestra?" , "Involved in swindling" .)