Waterlogged lair on turf (6)
I believe the answer is:
sodden
'waterlogged' is the definition.
(I've seen this in another clue)
'lair on turf' is the wordplay.
'lair' becomes 'den' (synonyms).
'on' is a charade indicator (letters next to each other).
'turf' becomes 'sod' (synonyms).
'den' after 'sod' is 'SODDEN'.
(Other definitions for sodden that I've seen before include "Soaking wet" , "Totally saturated" , "Soaked to the skin" , "heavy with moisture" , "Made very wet" .)