Surgery as answer to disease that in extremis takes time (9)

'surgery' is the definition.
(surgery done using a curette)

'answer to disease that in extremis takes time' is the wordplay.
'answer to disease' becomes 'cure'.
'in extremis' says to hollow out the word (remove centre letters) (only the letters on the extremes are used).
'takes' says to put letters next to each other.
'time' becomes 'age' (age is a kind of time).
'that' with its middle taken out is 'tt'.
'cure'+'tt'+'age'='CURETTAGE'

'as' acts as a link.