Son quietly studied feast (6)
I believe the answer is:
spread
'feast' is the definition.
(thesaurus)
'son quietly studied' is the wordplay.
'son' becomes 's'.
'quietly' becomes 'p' (p for piano and quiet).
'studied' becomes 'read' (I've seen this before).
's'+'p'+'read'='SPREAD'
(Other definitions for spread that I've seen before include "extended" , "Open out; range" , "Parsed (anag.)" , "Disseminate through padres" , "Generous meal" .)