Head of security is in a position to get help (10)
I believe the answer is:
assistance
'help' is the definition.
('assistance' can be a synonym of 'help')
'head of security is in a position' is the wordplay.
'head of' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'position' becomes 'stance' (stance is a kind of position**).
The first letter of 'security' is 's'.
's'+'is'='sis'
'a'+'stance'='astance'
'sis' going inside 'astance' is 'ASSISTANCE'.
'to get' is the link.
(Other definitions for assistance that I've seen before include "Aid" , "Help" , "Support" .)