Theatre critic, one producing disengaged bollocks? (9)

'disengaged bollocks?' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'theatre critic one' is the wordplay.
I cannot really understand how this works, but
'critic' could be 'rater' (I've seen this in another clue) and 'rater' is present in the answer.
'one' could be 'a' (a thing is one thing) and 'a' is found within the answer.
The remaining letters 'cst' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'producing' is the link.

Can you help me to learn more?