One putting right European in terrific mess (9)
I believe the answer is:
rectifier
'one putting right' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'european in terrific mess' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'in' means one lot of letters goes inside another.
'mess' is an anagram indicator.
'terrific' with letters rearranged gives 'rectifir'.
'e' inserted within 'rectifir' is 'RECTIFIER'.
Can you help me to learn more?
(Other definitions for rectifier that I've seen before include "Device for changing AC to DC current" , "Device such as a diode" , "which allows smooth flow" , "Electrical device converting AC to DC" , "I provide a remedy" .)