Get rid of dreadful boils in a hospital (7)
I believe the answer is:
abolish
'get rid of' is the definition.
('abolish' can be a synonym of 'get rid of')
'dreadful boils in a hospital' is the wordplay.
'dreadful' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'hospital' becomes 'h'.
'boils' is an anagram of 'bolis'.
'a'+'h'='ah'
'bolis' going into 'ah' is 'ABOLISH'.
(Other definitions for abolish that I've seen before include "Annul - expunge" , "Terminate" , "Annul - eradicate" , "Do away with - end" , "ditch" .)