Frightening people consequently turning on head of security (5)
I believe the answer is:
ogres
'frightening people' is the definition.
The answer and definition can be both people as well as being plural nouns.
Maybe there's an association between them I don't understand?
'consequently turning on head of security' is the wordplay.
'consequently turning' becomes 'og' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' becomes 're' (regarding).
'head of' suggests taking the first letters.
The first letter of 'security' is 's'.
'og'+'re'+'s'='OGRES'
Can you help me to learn more?
(Other definitions for ogres that I've seen before include "Giants in fairytales" , "Beasts" , "Monstrous giants and man-eaters" , "Fairytale giants" , "'Monsters, fiends (5)'" .)