Pegs in river (4)
I believe the answer is:
tees
I believe this clue is a double definition.
'pegs' is the first definition.
(tee is a kind of peg)
'river' is the second definition.
(River Tees)
'in' acts as a link.
(Other definitions for tees that I've seen before include "Current" , "English river" , "Golf pegs" , "often damaged by drivers" , "Middlesbrough's river" .)