Repeal binding regulation, one originally set in stone (8)
I believe the answer is:
abrogate
'repeal' is the definition.
(I've seen this in another clue)
'binding regulation one originally set in stone' is the wordplay.
'originally' says to take the initial letters.
'set in' means one lot of letters goes inside another.
'stone' becomes 'agate' (agate is a type of stone).
The initial letters of 'binding regulation one' is 'bro'.
'bro' going into 'agate' is 'ABROGATE'.
(Other definitions for abrogate that I've seen before include "Formally cancel (an agreement)" , "Cancel or repeal, say a law" , "Get rid of" , "Rescind" , "stop" .)