Trust Mark (4)
I believe the answer is:
tick
I believe this is a double definition.
'trust' is the first definition.
(thesaurus)
'mark' is the second definition.
(I've seen this before)
(Other definitions for tick that I've seen before include "Credit; mark as correct" , "Parasite, moment (colloq.)" , "Second" , "Parasite - mark of approval" , "Credit - bloodsucker" .)