Excellent account by Bede, ultimately (3)
I believe the answer is:
ace
'excellent' is the definition.
(I've seen this before)
'account by bede ultimately' is the wordplay.
'account' becomes 'ac'.
'by' says to put letters next to each other.
'ultimately' indicates one should take the final letters.
The final letter of 'bede' is 'e'.
'ac'+'e'='ACE'
(Other definitions for ace that I've seen before include "High card" , "hotshot" , "Hole in one; card" , "winner in court" , "first-class" .)