Take away the remainder, say (5)
I believe the answer is:
wrest
'take away' is the definition.
(I've seen this in another clue)
'remainder say' is the wordplay.
'remainder' becomes 'rest' (synonyms).
'say' shows a homophone (sound like).
'rest' sounds like 'WREST'.
'the' is the link.
(Other definitions for wrest that I've seen before include "Take away by force" , "Forcibly pull (something from someone's grip)" , "Obtain forcibly" , "Seize forcibly" , "Take away forcibly" .)