One of these, party 2 (6)
I believe the answer is:
cluedo
'2' is the definition.
Both the definition and answer are singular nouns.
Maybe they are linked in a way I don't understand?
'one of these party' is the wordplay.
'one of' becomes 'clue' (I can't explain this - if you can you should give a lot more credence to this answer).
'these party' becomes 'do' (do is a kind of party).
'clue'+'do'='CLUEDO'
Can you help me to learn more?
(Other definitions for cluedo that I've seen before include "Detective game" , "Murder mystery board game" .)