Great Britain ordered oil ban (6)
I believe the answer is:
albion
'great britain' is the definition.
'albion' can be an answer for 'britain' (I've seen this before). I'm not sure about the 'great' bit.
'ordered oil ban' is the wordplay.
'ordered' indicates anagramming the letters.
'oil'+'ban'='oilban'
'oilban' anagrammed gives 'ALBION'.
Can you help me to learn more?
(Other definitions for albion that I've seen before include "Old or poetic name for Britain" , "Old word for England, sometimes called perfidious" , "Poetic name for old England" , "Old name for England, perhaps perfidious" , "Poetic Britain, sometimes perfidious" .)