Fellow bold, briefly, to dip in water seeing exotic aquatic bird (8,4)
I believe the answer is:
mandarin duck
'exotic aquatic bird' is the definition.
(type of aquatic bird)
'fellow bold briefly to dip in water' is the wordplay.
'fellow' becomes 'man' (fellow can mean a man).
'bold' becomes 'daring' (I've seen this in another clue).
'briefly' means to remove the last letter.
'to dip in water' becomes 'duck' (duck can mean to dip into water).
'daring' with its final letter taken off is 'darin'.
'man'+'darin'+'duck'='MANDARIN DUCK'
'seeing' acts as a link.
(Other definitions for mandarin duck that I've seen before include "Bird that can be cooked" , "Asian fowl" , "flier" .)