Speak at a location (7)
I believe the answer is:
address
This clue is a double definition.
'speak' is the first definition.
(synonyms)
'a location' is the second definition.
(address is a kind of location)
'at' is the link.
(Other definitions for address that I've seen before include "Call" , "Sermon - lodging" , "Speak to the residence" , "Art" , "directions in window" .)