Professional put through paces showed dissent (9)
I believe the answer is:
protested
'showed dissent' is the definition.
(to protest is to show dissent or disagreement)
'professional put through paces' is the wordplay.
'professional' becomes 'pro' (synonyms).
'put through paces' becomes 'tested' (to put someone through their paces is to test them).
'pro'+'tested'='PROTESTED'
(Other definitions for protested that I've seen before include "Uttered words of dissent" , "'Stood against, disagreed (9)'" , "Dissented, resisted" , "Demonstrated against, objected" , "Expressed disapproval, objected" .)