Supporting part of the hospital in advance! (7)
I believe the answer is:
forward
'in advance' is the definition.
(thesaurus)
'supporting part of the hospital' is the wordplay.
'supporting' becomes 'for'.
'part of the hospital' becomes 'ward' ('ward' is part of 'hospital').
'for'+'ward'='FORWARD'
(Other definitions for forward that I've seen before include "going on" , "Bold, overfamiliar" , "left-winger, maybe" , "Send on; football player" , "Footballer; ahead in time" .)