Number of 3s very happy stripping sides on cupboard (5,2,3)

'number of 3s' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'very happy stripping sides on cupboard' is the wordplay.
'very happy' becomes 'joyous' (I've seen this before).
'stripping sides' means to look at the middle letters (the sides of the word are removed).
'on' is a charade indicator (letters next to each other).
'cupboard' becomes 'closet' (type of cupboard).
The centre of 'joyous' is 'oyou'.
'oyou' put after 'closet' is 'CLOSE TO YOU'.

Can you help me to learn more?