Require sound massage (5)
I believe the answer is:
knead
'massage' is the definition.
(I know that massage can be written as knead)
'require sound' is the wordplay.
'require' becomes 'need' (synonyms).
'sound' indicates a 'sounds like' (homophone) clue.
'need' is a homophone of 'KNEAD'.
(Other definitions for knead that I've seen before include "Work (dough/clay)" , "Work with finger movements" , "Work dough or massage flesh" , "Somehow work in" , "Massage with hands" .)