A professional stand-in (5)
I believe the answer is:
locum
This clue might be a double definition.
'a professional' is the first definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'stand-in' is the second definition.
(I know that locum is a type of stand-in)
Can you help me to learn more?
(Other definitions for locum that I've seen before include "Stand-in, for a doctor say" , "Stand-in physician" , "Doctor's temporary replacement" , "Professional who stands in for another" , "Medical temp?" .)