Work schedule is revolutionary inside sanatoriums (4)
I believe the answer is:
rota
'work schedule' is the definition.
(I've seen this before)
'revolutionary inside sanatoriums' is the wordplay.
'revolutionary' shows that the letters should be reversed in order.
'inside' indicates the answer is hidden within the clue.
'ator' is hidden within 'sanatoriums'.
'ator' back-to-front is 'ROTA'.
'is' acts as a link.
(Other definitions for rota that I've seen before include "Cycle of duty" , "Repetitious canon" , "Work roster" , "Work schedule" , "Duty roster" .)