He shouts at guest (6)
I believe the answer is:
caller
'guest' is the definition.
(I've seen this in another clue)
'he shouts' is the wordplay.
I cannot quite understand how this works, but
'he' could be 'cal' and 'cal' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'at' is the link.
Can you help me to learn more?
(Other definitions for caller that I've seen before include "Someone phoning" , "One paying a brief visit" , "One visits" , "Person on the line" , "Visitor" .)