Boundless disturbance reportedly held sway (12)
I believe the answer is:
unrestrained
'boundless' is the definition.
(thesaurus)
'disturbance reportedly held sway' is the wordplay.
I cannot really understand how this works, but
'disturbance' could be 'unrest' (I've seen this in another clue) and 'unrest' is located in the answer.
The remaining letters 'rained' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for unrestrained that I've seen before include "Unchecked" , "Wild" , "Not held back" , "spreading everywhere?" , "Without control" .)