Ignorant drunk uses cell (8)
I believe the answer is:
clueless
'ignorant' is the definition.
(I've seen this before)
'drunk uses cell' is the wordplay.
'drunk' is an anagram indicator.
'uses'+'cell'='usescell'
'usescell' with letters rearranged gives 'CLUELESS'.
(Other definitions for clueless that I've seen before include "With no idea" , "sort of crossword that nobody can solve?" , "Ignorant; helpless" , "Completely at sea about what's going on" , "Lacking knowledge and ability (informal)" .)