Visitor formulated conclusion audibly (5)
I believe the answer is:
guest
'visitor' is the definition.
(someone visiting a place)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for guest that I've seen before include "Visitant" , "who takes hotel room" , "See 2" , "Visitor, lodger" , "Conjectured audibly" .)