Envoy's no time to get certificate (7)
I believe the answer is:
diploma
'certificate' is the definition.
(diploma is a kind of certificate)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for diploma that I've seen before include "documentation" , "degree certificate" , "Certificate awarded by college for educational attainment" , "Certificate of education" , "What a student seeks" .)