Former knight seen timelessly as model (8)
I believe the answer is:
exemplar
'model' is the definition.
(I know that model can be written as exemplar)
'former knight seen timelessly' is the wordplay.
I cannot really see how this works, but
'former' could be 'ex' (prefix meaning former or onetime) and 'ex' is present in the answer.
This explanation may well be incorrect...
'as' is the link.
Can you help me to learn more?
(Other definitions for exemplar that I've seen before include "Epitome" , "Ideal model" , "Model to be followed" , "Typical specimen" , "A model or instance" .)