Nurses in East End sanatorium (5)
I believe the answer is:
tends
'nurses' is the definition.
(I've seen this before)
'in east end sanatorium' is the wordplay.
'in' says the answer is hidden in the clue.
'TENDS' can be found hidden inside 'east end sanatorium'.
(Other definitions for tends that I've seen before include "Inclines or looks after" , "Leans" , "Dents (anag.)" , "Shows an inclination" , "Is inclined" .)