Location of which a great deal is heard (4)
I believe the answer is:
site
'location of which' is the definition.
'site' can be an answer for 'location' (site is a kind of location). I am unsure of the remainder of the definition.
'a great deal is heard' is the wordplay.
'a great deal' becomes 'sight' ('sight' can be a synonym of 'great deal').
'is heard' indicates a 'sounds like' (homophone) clue.
'sight' is a homophone of 'SITE'.
Can you help me to learn more?
(Other definitions for site that I've seen before include "station" , "Area set aside for building" , "Location (of building, dig etc)" , "Ties into building location" , "Situation (of a building)" .)