Cannon to right and left of one by decree (9)
I believe the answer is:
ordinance
'decree' is the definition.
(I've seen this before)
'cannon to right and left of one' is the wordplay.
I cannot quite see how this works, but
'right' could be 'r' (abbreviation) and 'r' is located in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is found within the answer.
'of' could be 'o' and 'o' is present in the answer.
'one' could be 'an' (an apple is one apple) and 'an' is found in the answer.
The remaining letters 'dice' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'by' acts as a link.
Can you help me to learn more?
(Other definitions for ordinance that I've seen before include "practice" , "religious service maybe" , "Edict, order" , "Canon" , "Command" .)