How a violin concerto is played dishonestly (2,3,6)
I believe the answer is:
on the fiddle
'concerto is played dishonestly' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'how a violin' is the wordplay.
I cannot quite see how this works, but
'violin' could be 'fiddle' (synonyms) and 'fiddle' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for on the fiddle that I've seen before include "leader of the orchestra?" , "Engaged in cheating" , "Dishonest" , "Involved in swindling" , "Cheating (colloq.)" .)