Visitor's petition to keep danger curtailed (7)
I believe the answer is:
tourist
'visitor's' is the definition.
(eg someone visiting another country)
'petition to keep danger curtailed' is the wordplay.
'petition to' becomes 'tout' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'keep' means one lot of letters goes inside another.
'danger' becomes 'risk' (risk is a kind of danger).
'curtailed' means to remove the last letter.
'risk' with its last letter removed is 'ris'.
'tout' enclosing 'ris' is 'TOURIST'.
Can you help me to learn more?
(Other definitions for tourist that I've seen before include "Sightseeing traveller" , "Traveller for pleasure" , "Holiday visitor" , "One travels for pleasure" , "Holiday traveller" .)