Atypical (7)
(Other definitions for deviant that I've seen before include "Diverging from acceptable behaviour" , "Twisted" , "not behaving properly?" , "wayward" , "Diverging from the norm or from truth" .)
'atypical' is the definition.
(I know that atypical can be written as irregular)
This is the entire clue.
(Other definitions for irregular that I've seen before include "Unsymmetrical; soldier" , "somewhat odd" , "Unpunctual" , "unprincipled" , "Not uniform" .)