Open university about to make an approach (8)
I believe the answer is:
overture
'an approach' is the definition.
('overture' can be a synonym of 'approach')
'open university about' is the wordplay.
'open' becomes 'overt' ('overt' is associated in meaning with 'open').
'university about' becomes 'ure' (I've seen this in other clues).
'overt'+'ure'='OVERTURE'
'to make' is the link.
(Other definitions for overture that I've seen before include "Introductory section" , "offer" , "Opening music" , "Orchestral opener" , "Introductory music" .)