Hounds struggling in river (6)
I believe the answer is:
hudson
'river' is the definition.
(I know that Hudson is a river)
'hounds struggling' is the wordplay.
'struggling' indicates anagramming the letters (the letters struggle or wriggle into a new form).
'hounds' is an anagram of 'HUDSON'.
'in' is the link.
(Other definitions for hudson that I've seen before include "New York river; Upstairs/ Downstairs butler" , "American banker" , "Rock -, - bay" , "River in New York city" , "Major inland sea of NE Canada - . . . . . . Bay" .)