Park official called Queen (6)
I believe the answer is:
ranger
'park official' is the definition.
(I've seen this in another clue)
'called queen' is the wordplay.
'called' becomes 'rang' (called on the phone).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'rang'+'er'='RANGER'
(Other definitions for ranger that I've seen before include "Forest or park officer" , "Keeper of national park or Texas policeman" , "Rover" , "Forest or park keeper" , "Forest official" .)