Incompetent work on piano - tricky getting round that (6)
I believe the answer is:
sloppy
'incompetent' is the definition.
(sloppy can mean poorly done)
'work on piano tricky getting round that' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'on' is an insertion indicator (as in clothing 'on' a person).
'piano' becomes 'p' (musical abbreviation).
'tricky' becomes 'sly' (synonyms).
'getting round that' indicates putting letters inside.
'op' going around 'p' is 'opp'.
'opp' inserted into 'sly' is 'SLOPPY'.
(Other definitions for sloppy that I've seen before include "Casual; sentimental" , "Lacking neatness and order" , "Slipshod" , "Careless and messy" , "Romantic" .)