Patron supposed to be heard? (5)
I believe the answer is:
guest
'patron' is the definition.
'supposed to be heard?' is the wordplay.
'supposed' becomes 'guessed' ('guess' can be a synonym of 'suppose').
'to be heard?' indicates a 'sounds like' (homophone) clue.
'guessed' is a homophone of 'GUEST'.
(Other definitions for guest that I've seen before include "Visitor to whom hospitality is extended" , "Caller" , "Visitant" , "Recipient of hospitality" , "See 2" .)