Peter's lad out getting drunk (9)
I believe the answer is:
plastered
'drunk' is the definition.
(thesaurus)
'peter's lad out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'peters'+'lad'='peterslad'
'peterslad' with letters rearranged gives 'PLASTERED'.
'getting' acts as a link.
(Other definitions for plastered that I've seen before include "incapable" , "Very drunk (colloq.)" , "Drunk - applied coating to a wall" , "Pickled" , "under the table?" .)