Finally wave bye bye and go out (3)
I believe the answer is:
ebb
'go out' is the definition.
(I've seen this before)
'finally wave bye bye' is the wordplay.
'finally' says to take the final letters.
'bye' becomes 'b'.
'bye' becomes 'b'.
The last letter of 'wave' is 'e'.
'e'+'b'+'b'='EBB'
'and' acts as a link.
(Other definitions for ebb that I've seen before include "Flow outwards" , "Go out like tide (3)" , "Not to wax" , "Initially Mrs Browning's" , "Go out or recede like tide" .)