Important supply acquired by hospital department (7)
I believe the answer is:
eminent
'important' is the definition.
(similar in meaning)
'supply acquired by hospital department' is the wordplay.
'supply' becomes 'mine' (a mine is a supply of something).
'acquired by' indicates putting letters inside.
'hospital department' becomes 'ENT' (abbreviation for Ear, Nose and Throat department).
'mine' inserted within 'ent' is 'EMINENT'.
(Other definitions for eminent that I've seen before include "Lofty; famous" , "Met nine who were distinguished" , "Respected; notable" , "High" , "Outstanding or distinguished (7)" .)