Drunk is inane and idiotic (7)
I believe the answer is:
asinine
'idiotic' is the definition.
(both can mean foolish or silly)
'drunk is inane' is the wordplay.
'drunk' is an anagram indicator.
'is'+'inane'='isinane'
'isinane' anagrammed gives 'ASININE'.
'and' acts as a link.
(Other definitions for asinine that I've seen before include "Foolish like donkey" , "Foolish, silly" , "Senseless" , "Stubborn" , "'Mindless, vacuous (7)'" .)