Proposal Open University engineers (8)
I believe the answer is:
overture
'proposal' is the definition.
(I've seen this before)
'open university engineers' is the wordplay.
'open' becomes 'overt' ('overt' is associated in meaning with 'open'**).
'university' becomes 'u'.
'engineers' becomes 're' (Royal Engineers).
'overt'+'u'+'re'='OVERTURE'
(Other definitions for overture that I've seen before include "Orchestral opener" , "Orchestral work" , "Musical prelude to opera or ballet" , "Introductory music" , "Tender - piece of music" .)