Noisily speculated about visitor (5)
I believe the answer is:
guest
'visitor' is the definition.
(guest is a kind of visitor)
'noisily speculated' is the wordplay.
'noisily' shows a homophone (sound like).
'speculated' becomes 'guessed' (guessing is a kind of speculating).
'guessed' sounds like 'GUEST'.
'about' acts as a link.
(Other definitions for guest that I've seen before include "One receiving hospitality" , "One who's invited" , "Invited visitor" , "Conjectured audibly" , "Hotel resident" .)