Visitor caught everyone with Queen (6)
I believe the answer is:
caller
'visitor' is the definition.
(caller is a kind of visitor)
'caught everyone with queen' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'everyone' becomes 'all' (I've seen this before).
'with' says to put letters next to each other.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'c'+'all'+'er'='CALLER'
(Other definitions for caller that I've seen before include "One paying a brief visit" , "Person on the line" , "One visits" , "Visitor" , "Someone phoning" .)