Object to a change restricting trainees and middle men (9)
I believe the answer is:
challenge
'object to' is the definition.
(I've seen this before)
'a change restricting trainees and middle men' is the wordplay.
'restricting' means one lot of letters goes inside another.
'trainees' becomes 'll' (an abbreviation for learner driver written twice).
'and' says to put letters next to each other.
'middle' indicates the central letters.
The centre of 'men' is 'e'.
'll'+'e'='lle'
'change' placed around 'lle' is 'CHALLENGE'.
(Other definitions for challenge that I've seen before include "Dare; defy" , "difficult feat" , "Disagree!" , "Impugn; difficult task" , "Defy, confront" .)