Admit nine Euros went oddly missing in collection plates (6,3)
I believe the answer is:
dinner set
'collection plates' is the definition.
(collection of plates)
'admit nine euros went oddly missing' is the wordplay.
'oddly missing' means one should take alternating letters.
'admit'+'nine'+'euros'+'went'='admitnineeuroswent'
The alternating letters of 'admitnineeuroswent' are 'DINNER-SET'.
'in' acts as a link.
(Other definitions for dinner set that I've seen before include "China" , "Collection of plates and dishes" , "Complete service of plates and dishes for a meal" , "crockery" , "might be taken out for a meal" .)