They may spread disease in clever minds (6)
I believe the answer is:
vermin
'they may spread disease' is the definition.
The definition suggests an adverb but the answer is not.
'in clever minds' is the wordplay.
'in' indicates the answer is hidden within the clue.
'VERMIN' can be found hidden inside 'clever minds'.
Can you help me to learn more?
(Other definitions for vermin that I've seen before include "Unwanted creature(s)" , "Odious creatures" , "Harmful or disease-carrying creatures" , "Rats, mice, foxes and other harmful creatures" , "Common animals and birds, like rats and crows" .)