A rapacious creature, I managed hospital area under parking (7)
I believe the answer is:
piranha
'a rapacious creature' is the definition.
'i managed hospital area under parking' is the wordplay.
'managed' becomes 'ran' (I've seen this before).
'hospital' becomes 'h'.
'area' becomes 'a' (maths abbreviation).
'under' is a charade indicator (letters next to each other).
'parking' becomes 'p'.
'i'+'ran'+'h'+'a'='iranha'
'iranha' put after 'p' is 'PIRANHA'.
(Other definitions for piranha that I've seen before include "Voracious tropical fish" , "Ferocious fish" , "Voracious river fish" , "This predator" , "Small carnivorous freshwater fish" .)