Boatman seen in pub? Wow! (6)
I believe the answer is:
bargee
'boatman' is the definition.
(I've seen this before)
'pub? wow' is the wordplay.
'pub?' becomes 'bar' (both are drinking establishments).
'wow' becomes 'gee' (I've seen this in another clue).
'bar'+'gee'='BARGEE'
'seen in' acts as a link.
(Other definitions for bargee that I've seen before include "Canal worker" , "boatman" , "Boat operator" , "River/canal boat worker" , "Lighterman" .)