Obscure European coin (4)
I believe the answer is:
dime
'coin' is the definition.
(dime is a kind of coin)
'obscure european' is the wordplay.
'obscure' becomes 'dim' (I've seen this before).
'european' becomes 'e' (abbreviation e.g. EU).
'dim'+'e'='DIME'
(Other definitions for dime that I've seen before include "Small American coin" , "Ten US cents" , "Foreign coin" , "US ten cent piece" , "US coin, one-tenth of a dollar" .)