Nobody special, that's all (8)
I believe the answer is:
everyone
'all' is the definition.
(I've seen this before)
'nobody special that's' is the wordplay.
I cannot really see how this works, but
'that' could be 'yon' (archaic term meaning 'that') and 'yon' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for everyone that I've seen before include "All and sundry" , "Uncle Tom Cobleigh and all" , "the masses" , "All the people" , "Entire group" .)