Royal monogram in Ireland (4)
I believe the answer is:
erin
'ireland' is the definition.
(poetic name for Ireland)
'royal monogram in' is the wordplay.
I cannot quite understand how this works, but
'royal' could be 'er' (abbreviation for Elizabeth Regina) and 'er' is located in the answer.
'in' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for erin that I've seen before include "Another name for 11 ac" , "(Literary name for) Ireland" , "that faces Atlantic" , "Poetic name for Ireland" , "Poetically, Ireland" .)