Fake coins found in Ireland — one's coated in enamel (7)
I believe the answer is:
incisor
'one's coated in enamel' is the definition.
(incisor is a type of tooth)
'fake coins found in ireland' is the wordplay.
'fake' indicates an anagram (I've seen this in other clues).
'found in' is an insertion indicator.
'ireland' becomes 'ir' (abbreviation for Ireland).
'coins' is an anagram of 'nciso'.
'nciso' put into 'ir' is 'INCISOR'.
(Other definitions for incisor that I've seen before include "companion could be Goofy" , "Chisel-edged tooth" , "Front tooth" , "Type of tooth" , "One takes a bite" .)