Advice, say, to ignore a drunk (5)
I believe the answer is:
tipsy
'drunk' is the definition.
(thesaurus)
'advice say to ignore a' is the wordplay.
'advice' becomes 'tip' (I've seen this before).
'to ignore' suggests deleting specific letters.
'say' with 'a' taken away is 'sy'.
'tip'+'sy'='TIPSY'
(Other definitions for tipsy that I've seen before include "A bit drunk" , "affected by drink" , "Inebriated" , "Slightly intoxicated" , "Merry, squiffy" .)