Best team, until beaten after losing lead in Newcastle (8)
I believe the answer is:
ultimate
'best' is the definition.
(I've seen this before)
'team until beaten after losing lead in newcastle' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'team' is 'mate' which is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ultimate that I've seen before include "The last element of a series" , "Happening at the end of a process, final" , "Utmost; last" , "Last or concluding element" , "Best or most extreme" .)