VIP was keen re new special screening (5,7)
I believe the answer is:
sneak preview
'special screening' is the definition.
(I've seen this in another clue)
'vip was keen re new' is the wordplay.
'new' indicates anagramming the letters.
'vip'+'was'+'keen'+'re'='vipwaskeenre'
'vipwaskeenre' is an anagram of 'SNEAK PREVIEW'.
(Other definitions for sneak preview that I've seen before include "Public showing of a film before general release" , "Unannounced screening" , "Private screening or viewing of new film etc." , "Test screening before general release" .)