Require, say, to work dough (5)
I believe the answer is:
knead
'work dough' is the definition.
(I've seen this in another clue)
'require say' is the wordplay.
'require' becomes 'need' (synonyms).
'say' shows a homophone (sound like).
'need' is a homophone of 'KNEAD'.
'to' is the link.
(Other definitions for knead that I've seen before include "Work (dough) into mass" , "Work flour into dough manually" , "Manipulate" , "Pummel dough" , "Work (dough/clay)" .)