The sort to work at a keyboard (4)
I believe the answer is:
type
I believe this clue is a double definition.
'the sort' is the first definition.
(type is a kind of sort)
'work at a keyboard' is the second definition.
(I've seen this in another clue)
'to' acts as a link.
(Other definitions for type that I've seen before include "get words on to paper?" , "Class, kind or printed characters" , "Write letters" , "of a certain kind" , "Kind; set in print" .)