Firm evidence in print (5)
I believe the answer is:
proof
This clue could be a double definition.
'firm evidence' is the first definition.
'proof' can be an answer for 'evidence' (evidence proves something). I'm not certain of the 'firm' bit.
'print' is the second definition.
(thesaurus)
'in' is the link.
Can you help me to learn more?
(Other definitions for proof that I've seen before include "Demonstration of the truth of something" , "Factual evidence" , "a writer may check" , "Exposition ending QED?" , "Body of evidence" .)