Violent genre leads to attention deficit disorder (7)
I believe the answer is:
derange
'disorder' is the definition.
(I know that derange is a type of disorder)
'violent genre leads to attention deficit' is the wordplay.
'violent' indicates anagramming the letters.
'leads to' indicates taking the first letters.
The initial letters of 'attention deficit' is 'ad'.
'genre'+'ad'='genread'
'genread' anagrammed gives 'DERANGE'.
(Other definitions for derange that I've seen before include "Make mad" , "cause confusion" , "Upset" , "Unhinge" , "Madden" .)