Sound advice for local authority (7)
I believe the answer is:
council
'local authority' is the definition.
(I've seen this before)
'sound advice' is the wordplay.
'sound' shows a homophone (sound like).
'advice' becomes 'counsel' (I've seen this in another clue).
'counsel' is a homophone of 'COUNCIL'.
'for' acts as a link.
(Other definitions for council that I've seen before include "Body of lawmakers" , "County administrators" , "Body found in town hall" , "Town or county assembly" , "Sacerdotal garment" .)