Radio announcement’s to recognise a worry: coastal fog (3,4)
I believe the answer is:
sea fret
'coastal fog' is the definition.
'radio announcement's to recognise a worry' is the wordplay.
'radio announcement's' indicates a 'sounds like' (homophone) clue.
'to recognise' becomes 'see' (I've seen this before).
'a worry' becomes 'fret' (I've seen this before).
'see' sounds like 'sea'.
'sea'+'fret'='SEA-FRET'
(Other definitions for sea fret that I've seen before include "Threat to visibility" , "coastal haze" , "onshore mist" , "Coastal mist" , "North Sea haar, for instance" .)