Aching heart consumes Simon King returning from "green country" (5)
I believe the answer is:
irish
'green country' is the definition.
'Irish' can be an answer for 'country' (Irish is an example). I'm unsure of the 'green' bit.
'aching heart consumes simon king returning' is the wordplay.
'heart' means to look at the middle letters.
'consumes' indicates putting letters inside.
'simon king' becomes 'sir' (I can't explain this - if you can you should believe this answer much more).
'returning' says the letters should be written backwards.
The middle of 'aching' is 'hi'.
'hi' going around 'sir' is 'hsiri'.
'hsiri' written backwards gives 'IRISH'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for irish that I've seen before include "Native to the Emerald Isle" , "Reddish-brown dog" , "From Eire" , "Hi, Sir, ar you a Celt?" , "One setter" .)