Employed in house decorating (4)
I believe the answer is:
used
'employed' is the definition.
('use' can be a synonym of 'employ')
'in house decorating' is the wordplay.
'in' says the answer is hidden in the clue.
'USED' is hidden within 'house decorating'.
(Other definitions for used that I've seen before include "Brought into service" , "Of clothes or cars, second-hand" , "Dues (anag.)" , "Exploited - not new" , "Accustomed, having been put into service" .)