Some pretty petulant sort (4)
I believe the answer is:
type
'sort' is the definition.
(type is a kind of sort)
'some pretty petulant' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'TYPE' is hidden in the letters of 'pretty petulant'.
(Other definitions for type that I've seen before include "Courier for example" , "Genre" , "Sort - way to write" , "get words on to paper?" , "Sort; printed letters" .)