Religious adherent's request to be heard (4)
I believe the answer is:
sikh
'religious adherent's' is the definition.
(I've seen this before)
'request to be heard' is the wordplay.
'request' becomes 'seek' (I've seen this in another clue).
'to be heard' shows a homophone (sound like).
'seek' is a homophone of 'SIKH'.
(Other definitions for sikh that I've seen before include "Follower of gurus" , "Member of Indian religious group, wears turban" , "Follower of religion founded by Guru Nanak" , "Disciple in Sanskrit" , "Turbanned believer" .)