Unblemished and trusted student about to suffer a setback (7)
I believe the answer is:
perfect
'unblemished' is the definition.
(similar in meaning)
'trusted student about to suffer a setback' is the wordplay.
I cannot really understand how this works, but
'about' could be 'c' (abbreviation for circa) and 'c' is located in the answer.
'a' could be 'per' (eg 'one a day' means 'one per day') and 'per' is found in the answer.
The remaining letters 'fet' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for perfect that I've seen before include "Without blemish" , "Make right" , "Getting by scheming" , "Mature" , "Ideal, flawless" .)