Go and foolishly trade a piano in (6)
I believe the answer is:
depart
'go' is the definition.
(synonyms)
'foolishly trade a piano in' is the wordplay.
'foolishly' is an anagram indicator.
'a piano' becomes 'p' (musical abbreviation).
'in' means one lot of letters goes inside another.
'trade' is an anagram of 'deart'.
'deart' placed around 'p' is 'DEPART'.
'and' acts as a link.
(Other definitions for depart that I've seen before include "Make an exit" , "Quit" , "Prated (anag.)" , "Start out" , "Stray" .)