Ex US President exposed, truth will be of interest to historians (8)
I believe the answer is:
artefact
'ex us president' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'exposed truth will be of interest to historians' is the wordplay.
I cannot really see how this works, but
'truth' could be 'fact' (I've seen this before) and 'fact' is located in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for artefact that I've seen before include "Man-made object, of archaeological interest, perhaps" , "Thing made by human workmanship" , "Item made by human" , "Human-made object" , "Man-made object, of archaeological interest say" .)