Flood ruins renovated hospital (6)
I believe the answer is:
inrush
'flood' is the definition.
(I've seen this in another clue)
'ruins renovated hospital' is the wordplay.
'renovated' indicates anagramming the letters.
'hospital' becomes 'H' (abbreviation for hospital on maps).
'ruins' is an anagram of 'inrus'.
'inrus'+'h'='INRUSH'
(Other definitions for inrush that I've seen before include "Overwhelming flow" , "Inflow" , "hasty entrance" , "Sudden inward flow" , "Sudden surge" .)