Damp lawns treated for waterlogged area (9)
I believe the answer is:
swampland
'waterlogged area' is the definition.
(I've seen this before)
'damp lawns treated' is the wordplay.
'treated' indicates an anagram.
'damp'+'lawns'='damplawns'
'damplawns' with letters rearranged gives 'SWAMPLAND'.
'for' acts as a link.
(Other definitions for swampland that I've seen before include "Waterlogged area" , "boggy area" .)