Angry demand of shellfish gatherer heard (7)
I believe the answer is:
clamour
'angry demand' is the definition.
(clamour can mean an angry demand from the public)
'shellfish gatherer heard' is the wordplay.
'shellfish gatherer' becomes 'clammer' (someone who gathers clams).
'heard' shows a homophone (sound like).
'clammer' is a homophone of 'CLAMOUR'.
'of' acts as a link.
(Other definitions for clamour that I've seen before include "Noisy disturbance" , "Complaints" , "row" , "racket" , "Uproar" .)