Someone calling six riots off (7)
I believe the answer is:
visitor
'someone' is the definition.
(visitor is a kind of someone)
'calling six riots off' is the wordplay.
I cannot quite understand how this works, but
'six' could be 'vi' (Roman numerals) and 'vi' is found in the answer.
an anagram of 'riots' is 'sitor' which is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for visitor that I've seen before include "Seasonal migratory bird" , "Guest - tourist" , "Company" , "who might stay?" , "Caller, guest" .)