Daubed it on, being drunk (9)
I believe the answer is:
plastered
'daubed' is the definition.
('plaster' can be a synonym of 'daub')
'it on being drunk' is the wordplay.
I cannot really understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for plastered that I've seen before include "incapable" , "Coated thickly, being slangily drunk" , "Smashed" , "Drunk (slang)" , "the worse for drink" .)