Problem created by monarch introducing tax? The opposite (8)
I believe the answer is:
exercise
'problem' is the definition.
(eg a maths exercise)
'monarch introducing tax? the opposite' is the wordplay.
I cannot really see how this works, but
'monarch' could be 'er' (abbreviation for Elizabeth Regina, British Queen) and 'er' is located in the answer.
'tax?' could be 'excise' (excise is a kind of tax) and 'excise' is located in the remaining letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
'created by' is the link.
Can you help me to learn more?
(Other definitions for exercise that I've seen before include "Practice task" , "Physical exertion for keeping fit" , "written school task" , "Task for pupil" , "Healthy activity" .)