Remove top to drain large pitcher (4)
I believe the answer is:
ewer
'large pitcher' is the definition.
(I've seen this in another clue)
'remove top to drain' is the wordplay.
'remove top' means to remove the first letter (I've seen 'removes top' mean this).
'to drain' becomes 'sewer' (sewer is a kind of drain).
'sewer' with its first letter taken off is 'EWER'.
(Other definitions for ewer that I've seen before include "water-carrier" , "Big jug" , "Large water jug" , "Container" , "Large, wide-mouthed jug" .)