The turf's half waterlogged! (3)
I believe the answer is:
sod
'the turf's' is the definition.
(both can mean a piece of grass)
'half waterlogged' is the wordplay.
'half' means to take half the letters.
'waterlogged' becomes 'sodden' (I've seen this in another clue).
'sodden' cut in half is 'SOD'.
(Other definitions for sod that I've seen before include "Surface layer of ground with grass roots" , "A piece of sward." , "Piece of turf; a Law named for him" , "Lump of turf or unpleasant person" , "Lump of earth" .)