What vigilant people pay for treatment (9)
I believe the answer is:
attention
I believe this clue is a double definition.
'what vigilant people pay' is the first definition.
'treatment' is the second definition.
(I have seen 'special treatment' mean 'attention' so perhaps 'treatment' could also mean 'attention')
'for' is the link.
(Other definitions for attention that I've seen before include "Mental concentration or awareness( 9)" , "Order given on parade" , "order to stand still" , "notice" , "What students must pay" .)