Pointlessly, in the odd feud lit up place in Dublin (8)
I believe the answer is:
futilely
'pointlessly' is the definition.
(I've seen this before)
'odd feud lit up place in dublin' is the wordplay.
'odd' means one should take alternating letters.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'place in dublin' becomes 'ely' (I can't explain this - if you can you should give a lot more credence to this answer).
The alternate letters of 'feud' are 'fu'.
'lit' backwards is 'til'.
'fu'+'til'+'ely'='FUTILELY'
'in the' is the link.
Can you help me to learn more?
(Another definition for futilely that I've seen is " pointlessly".)