Sheep and rats emptied water containers (5)
I believe the answer is:
ewers
'water containers' is the definition.
(ewer is a type of jug for water)
'sheep and rats emptied' is the wordplay.
'sheep' becomes 'ewe' (ewe is a kind of sheep).
'and' says to put letters next to each other.
'emptied' means to remove the middle letters.
'rats' with its centre taken out is 'rs'.
'ewe'+'rs'='EWERS'
(Other definitions for ewers that I've seen before include "Jugs thrown into sewer" , "Large jugs" , "Vase-shaped jugs" , "Vessels with handle and spout" , "containers" .)