Proof of vice-president not taking trips (8)
I believe the answer is:
evidence
'proof' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for evidence that I've seen before include "Testimony - verification" , "Confirmation" , "material presented in court" , "Signs, indications" , "Knowledge on which to base belief" .)