Acts not allowed, as it happens (5,3)
I believe the answer is:
Here is my best explanation:
'as it happens' is the definition.
(I've seen this before)
'acts not allowed' is the subsidiary indication.
I cannot quite understand how this works, but
'acts' could be 'turns' (turn is a kind of act) and 'turns' is present in the answer.
'not allowed' could be 'out' (I've seen this before) and 'out' is present in the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).
(Other definitions for turns out that I've seen before include "as it happens", "Empties" and "Gives order of the boot".)