Doctor said, caught in racket, to show contempt (7)
I believe the answer is:
disdain
'contempt' is the definition.
('disdain' can be a synonym of 'contempt')
'doctor said caught in racket' is the wordplay.
'doctor' indicates an anagram.
'caught in' means one lot of letters goes inside another.
'racket' becomes 'din' (I've seen this before).
'said' anagrammed gives 'sdai'.
'sdai' going into 'din' is 'DISDAIN'.
'to show' is the link.
(Other definitions for disdain that I've seen before include "no respect" , "'Contempt, condescension (7)'" , "Mild contempt" , "Hauteur" , "Arrogance" .)