Ireland introducing minute eastern moth (6)
I believe the answer is:
ermine
'moth' is the definition.
(type of moth)
'ireland introducing minute eastern' is the wordplay.
'ireland' becomes 'erin' (poetic name for Ireland).
'introducing' is an insertion indicator (some letters introduced or inserted into others).
'minute' becomes 'm' (abbreviation).
'eastern' becomes 'e'.
'erin' placed around 'm' is 'ermin'.
'ermin'+'e'='ERMINE'
(Other definitions for ermine that I've seen before include "Stoat in its winter coat" , "Expensive white fur" , "Fur trimming on royal robes" , "Warm white covering" , "Winter fur of the stoat" .)