The isle to come back to? (4)
I believe the answer is:
erin
'the isle' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?
'come back to?' is the wordplay.
'back' indicates one should take the final letters (the letter at the back).
'to?' becomes 'rin' (I am not sure about this - if you are sure you should believe this answer much more).
The final letter of 'come' is 'e'.
'e'+'rin'='ERIN'
'to' is the link.
Can you help me to learn more?
(Other definitions for erin that I've seen before include "Literary term for Ireland" , "Ireland (poet.)" , "Another name for 11 ac" , "(Literary name for) Ireland" , "Early and poetic name here" .)