Dependent but first day fishing (8)
I believe the answer is:
dangling
'dependent' is the definition.
(thesaurus)
'first day fishing' is the wordplay.
'first day' becomes 'd' (1st letter of 'day').
'fishing' becomes 'angling' (angling is a kind of fishing).
'd'+'angling'='DANGLING'
'but' is the link.
(Other definitions for dangling that I've seen before include "Hanging loosely, swinging or swaying" , "Offering" , "Disconnected" .)