Officer surrounded by mounds of sand on southern headland (9)
I believe the answer is:
dungeness
'headland' is the definition.
(I've seen this before)
'officer surrounded by mounds of sand on southern' is the wordplay.
'officer' becomes 'gen' (abbreviation for general).
'surrounded by' indicates putting letters inside.
'mounds of sand' becomes 'dunes' (I've seen this in another clue).
'on' is a charade indicator (letters next to each other).
'southern' becomes 's' (abbreviation).
'gen' placed into 'dunes' is 'dungenes'.
'dungenes'+'s'='DUNGENESS'
(Other definitions for dungeness that I've seen before include "Nuclear power station site in Kent" , "Headland by Romney Marsh" , "Lighthouse on 12" , "Headland and power station in Kent" .)