One of The Greens in Dublin on course
I believe the answer is:
side dish
'one of the greens' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'in dublin on course' is the wordplay.
'in dublin' becomes 'side' (I can't justify this - if you can you should believe this answer much more).
'on' is a charade indicator (letters next to each other).
'course' becomes 'dish' (I've seen this before).
'side'+'dish'='SIDE-DISH'
Can you help me to learn more?
(Other definitions for side dish that I've seen before include "tasty companion?" , "Additional portion of food" , "extra food" , "Supplementary item at table" , "Food item subordinate to the main one" .)