Musician has piano in the jetty
I believe the answer is:
piper
'musician' is the definition.
(someone playing the bagpipes)
'piano in the jetty' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'in the' is an insertion indicator.
'jetty' becomes 'pier' (I've seen this before).
'p' inserted inside 'pier' is 'PIPER'.
'has' acts as a link.
(Other definitions for piper that I've seen before include "'Liam O'Flynn or Seamus Ennis, say (5)'" , "Wind instrumentalist" , "One playing wind instrument" , "Highland musician" , "oil and gas field" .)