Hangs key and goes fishing (7)
I believe the answer is:
dangles
'hangs' is the definition.
(dangling is a kind of hanging)
'key and goes fishing' is the wordplay.
'key' becomes 'd' (musical key).
'and' says to put letters next to each other.
'goes fishing' becomes 'angles' (I've seen this in another clue).
'd'+'angles'='DANGLES'
(Other definitions for dangles that I've seen before include "Temptingly display" , "Hangs freely" , "Hovers" , "Hangs loosely" .)