Vessels taking sheep over river (5)
I believe the answer is:
ewers
'vessels' is the definition.
(ewer is a kind of vessel)
'sheep over river' is the wordplay.
'sheep' becomes 'ewes' (a ewe is a female sheep).
'over' indicates putting letters inside.
'river' becomes 'r' (abbreviation).
'ewes' placed around 'r' is 'EWERS'.
'taking' acts as a link.
(Other definitions for ewers that I've seen before include "Water jugs" , "Jugs thrown into sewer" , "Vase-shaped jugs" , "containers" , "Vessels with handle and spout" .)