Rascal's trick piano (5)
I believe the answer is:
scamp
'rascal's' is the definition.
(synonyms)
'trick piano' is the wordplay.
'trick' becomes 'scam' (I've seen this in other clues).
'piano' becomes 'p' (musical abbreviation).
'scam'+'p'='SCAMP'
(Other definitions for scamp that I've seen before include "Tearaway" , "Troublemaker" , "villain" , "Scoundrel" , "Impish child" .)