Key worker? (6)
'key worker?' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for typist that I've seen before include "Person at keyboard" , "One using keyboard" , "Forerunner of the word processor operator" , "Pre-computer office worker" , "Worker taken from pool, perhaps" .)
(Other definitions for pianist that I've seen before include "Ashkenazy or Lang Lang" , "Ashkenazy, say" , "Key worker," , "Expert on keys" , "Key expert" .)