Work requirement, by the sound of it? (5)
I believe the answer is:
knead
'work' is the definition.
(I know that work can be written as knead)
'requirement by the sound of it?' is the wordplay.
'requirement' becomes 'need' (synonyms).
'by the sound of it?' shows a homophone (sound like).
'need' sounds like 'KNEAD'.
(Other definitions for knead that I've seen before include "Work together" , "Work (dough/clay)" , "Pummel dough" , "Work flour into dough manually" , "Work (dough) into mass" .)