Very old, or a new Euro coin impressing one (7)
I believe the answer is:
ancient
'very old' is the definition.
(I've seen this before)
'a new euro coin impressing one' is the wordplay.
'a new' becomes 'an' (I've seen this in other clues).
'euro coin' becomes 'cent' (cent is a kind of coin. I am not sure about the 'euro' bit.**).
'impressing' is an insertion indicator (impress historically meant to conscript).
'one' becomes 'i' (Roman numeral).
'cent' placed around 'i' is 'cient'.
'an'+'cient'='ANCIENT'
'or' is the link.
Can you help me to learn more?
(Other definitions for ancient that I've seen before include "Dating from long ago" , "Old man" , "Veteran" , "From the distant past" , "Extremely old" .)