Being an administrator is binding, keeping support in (11)

'being an' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

'administrator is binding keeping support in' is the wordplay.
'administrator' becomes 'trustee' (I've seen this before).
'is binding keeping support' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' becomes 'hip' (both can mean fashionable).
'trustee'+'s'+'hip'='TRUSTEESHIP'

Can you help me to learn more?