Shocked where flatbed barges drifting (13)
I believe the answer is:
flabbergasted
'shocked' is the definition.
(I've seen this in another clue)
'flatbed barges drifting' is the wordplay.
'drifting' is an anagram indicator.
'flatbed'+'barges'='flatbedbarges'
'flatbedbarges' anagrammed gives 'FLABBERGASTED'.
'where' is the link.
(Other definitions for flabbergasted that I've seen before include "Dumbfounded" , "Thunderstruck" , "Greatly surprised" , "Confounded" , "Gobsmacked" .)