About to get a bite, fishing (7)
I believe the answer is:
casting
'fishing' is the definition.
(casting is a kind of fishing)
'about to get a bite' is the wordplay.
'about to' becomes 'ca' (I've seen this in other clues).
'get' means one lot of letters go next to another.
'a bite' becomes 'sting' ('sting' can be a synonym of 'bite').
'ca'+'sting'='CASTING'
(Other definitions for casting that I've seen before include "Shaping in mould; assigning actors to" , "-- Vote; -- couch" , "Choosing actors" , "Shaping metal in mould" , "The process of selecting actors for play" .)