Slacking, paid less — only half (4)
I believe the answer is:
idle
'slacking' is the definition.
(both can mean not working)
'paid less only half' is the wordplay.
'only half' indicates the answer is hidden within the clue (only half of this group of letters).
'IDLE' is hidden in the letters of 'paid less'.
(Other definitions for idle that I've seen before include "Hang about doing nothing" , "Run out of gear" , "Reluctant to work - Pythonesque Eric" , "no longer employed?" , "Lazy - unemployed" .)