What the building worker did when drunk? (9)
I believe the answer is:
plastered
'drunk?' is the definition.
(slang term)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for plastered that I've seen before include "like walls and ceilings?" , "Paralytic (slang)" , "Drunk (slang)" , "Coated thickly, being slangily drunk" , "get soaked?" .)