Complete removing top from drain (5)
I believe the answer is:
utter
'complete' is the definition.
(I've seen this before)
'removing top from drain' is the wordplay.
'removing top from' means to remove the first letter.
'drain' becomes 'gutter'.
'gutter' with its first letter taken away is 'UTTER'.
(Other definitions for utter that I've seen before include "Make sounds (but not necessarily words)" , "Speak, express" , "Say - complete" , "issue" , "Speak or say" .)