Arch rival in Tyneside canteen, one gathered? (7)
I believe the answer is:
nemesis
'arch rival' is the definition.
'nemesis' can be an answer for 'rival' (I have seen 'Unbeatable rival ' mean 'nemesis' so perhaps 'rival' could also mean 'nemesis'). I am not sure about the 'arch' bit.
'tyneside canteen one gathered?' is the wordplay.
'tyneside' becomes 'ne' (region in North East of England).
'canteen' becomes 'mess' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'gathered?' indicates putting letters inside.
'mess' placed around 'i' is 'mesis'.
'ne'+'mesis'='NEMESIS'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for nemesis that I've seen before include "Agent of (someone's) downfall" , "Archenemy" , "Fate" , "Something causing misery (or death) - Meissen (anag)" , "Greek goddess - opponent who cannot be beaten" .)