International donor played, but not in the Open (6)
I believe the answer is:
indoor
'not in the open' is the definition.
(I've seen this before)
'international donor played' is the wordplay.
'international' becomes 'i' (abbreviation eg in IMF).
'played' indicates anagramming the letters.
'donor' anagrammed gives 'ndoor'.
'i'+'ndoor'='INDOOR'
'but' is the link.
(Other definitions for indoor that I've seen before include "covered" , "Situated within a building - maybe a sport" , "Located within a building" , "in chambers?" , "Within walls" .)