Part of dinghy on Derwent over there (6)
I believe the answer is:
yonder
'over there' is the definition.
(I've seen this before)
'part of dinghy on derwent' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'YONDER' is hidden within 'dinghy on derwent'.
(Other definitions for yonder that I've seen before include "See Rodney over there" , "Rodney (anag.)" , "Over there, somewhat archaic" , "Over there (poetic)" , "Over there, of old." .)