Some nasty lefty type (5)
I believe the answer is:
style
'type' is the definition.
(thesaurus)
'some nasty lefty' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'STYLE' is hidden in the letters of 'nasty lefty'.
(Other definitions for style that I've seen before include "Manner or look" , "Pointed pen" , "Chic" , "Former writer" , "Particular kind, of fashion say" .)