Remains of a small hospital? (3)
I believe the answer is:
ash
'remains' is the definition.
(I've seen this before)
'a small hospital?' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'hospital?' becomes 'h'.
'a'+'s'+'h'='ASH'
'of' acts as a link.
(Other definitions for ash that I've seen before include "Remnant from fire" , "-- Wednesday" , "Common tree" , "Wooden" , "Burnt remains; tree" .)