Sect has control over European banks (12)
I believe the answer is:
denomination
'sect' is the definition.
(I've seen this before)
'control over european banks' is the wordplay.
'control' becomes 'domination' (domination is a kind of control).
'over' indicates putting letters inside.
'european banks' becomes 'en' (I can't justify this - if you can you should give a lot more credence to this answer).
'domination' placed around 'en' is 'DENOMINATION'.
'has' acts as a link.
Can you help me to learn more?
(Other definitions for denomination that I've seen before include "Note's face value" , "Religious group - grade in series of designated values" , "Type of currency, religion etc" , "sect" , "Face value of a banknote, coin or postage stamp" .)