Certify, authorise (8)
I believe the answer is:
accredit
This clue is a double definition.
'certify' is the first definition.
(accrediting is a kind of certifying)
'authorise' is the second definition.
(I've seen this before)
(Other definitions for accredit that I've seen before include "Give authority or sanction to" , "Appoint" , "Red cacti (anag)" , "Give official recognition to" , "Endorse" .)