Obscure English coin (4)
I believe the answer is:
dime
'coin' is the definition.
(dime is a kind of coin)
'obscure english' is the wordplay.
'obscure' becomes 'dim' (I've seen this before).
'english' becomes 'e' (abbreviation).
'dim'+'e'='DIME'
(Other definitions for dime that I've seen before include "Ten-cent coin in America" , "One tenth of a US dollar" , "US 10 cent coin" , "US coin, one-tenth of a dollar" , "Ten cents piece" .)