The lady-love is in Ireland (4)
I believe the answer is:
mayo
'in ireland' is the definition.
The definition suggests a singular noun which matches the answer.
'the lady-love' is the wordplay.
'the lady' becomes 'may' (**).
'love' becomes 'o' (In tennis, 'love' means 'zero').
'may'+'o'='MAYO'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for mayo that I've seen before include "Irish county (county town, Castlebar)" , "Eg, Braeburn or Cox" , "County of Western Eire" , "You'll find it in the Emerald Isle" , "Salad dressing (informal)" .)