Work for a while that doctor may take, briefly (4)
I believe the answer is:
temp
This clue is a double definition.
'work for a while' is the first definition.
'that doctor may take briefly' is the second definition.
(a doctor may take your temperature or 'temp')
(Other definitions for temp that I've seen before include "Non-full time employee" , "Transient office worker" , "Short-time worker" , "Non-permanent worker" , "Transitory office worker" .)