Opening in Test, but only opening, getting run out (5)
I believe the answer is:
intro
'opening' is the definition.
(I've seen this before)
'test but only opening getting run out' is the wordplay.
'test but only opening getting' becomes 'int' (I can't explain this - if you can you should give a lot more credence to this answer).
'run out' becomes 'ro' (cricket abbreviation).
'int'+'ro'='INTRO'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for intro that I've seen before include "First passage of play" , "Early music piece" , "Brief passage to start a piece of popular music" , "First notes" , "Opening bars to a piece of popular music" .)