A strainer (5)
I believe the answer is:
sieve
'a strainer' is the definition.
(sieve is a kind of strainer)
This is all the clue.
(Other definitions for sieve that I've seen before include "Craft for Jumblies" , "Separate" , "Riddle, strain" , "Jumblies' vessel" , "Utensil for straining or sifting food" .)