Mark's successor, semi-neurotic? (4)

I believe the answer is:

euro

'mark's successor' is the definition.
(currency which replaced the German Mark)

'semi-neurotic?' is the wordplay.
'semi' says the answer is hidden in the clue (only some of the letters).
'EURO' can be found hidden inside 'neurotic'.

(Other definitions for euro that I've seen before include "Continental currency" , "European currency" , "Modern cross-border currency" , "France's unit of currency" , "Vatican currency" .)

I've seen this clue in The Guardian.

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