Scrub a can opener clean, perhaps (6)
I believe the answer is:
cancel
'scrub' is the definition.
(I've seen this before)
'a can opener clean perhaps' is the wordplay.
'opener' indicates taking the first letters.
'perhaps' indicates an anagram.
The first letter of 'can' is 'c'.
'clean' with letters rearranged gives 'ancel'.
'c'+'ancel'='CANCEL'
(Other definitions for cancel that I've seen before include "Call off (arranged event)" , "Scrub" , "Scrap" , "Write off" , "Officially prevent happening" .)