The kind to use a machine to write (4)
I believe the answer is:
type
'write' is the definition.
(I know that type is a more specific form of the action write)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for type that I've seen before include "Sort, kind" , "of a certain kind" , "Class, kind or category" , "Use keys" , "Kind; set in print" .)