Satisfied it's safe (4)
I believe the answer is:
sure
I believe this clue is a double definition.
'satisfied' is the first definition.
(thesaurus)
'safe' is the second definition.
(thesaurus)
'it's' acts as a link.
(Other definitions for sure that I've seen before include "Confident sort of ruse" , "Agreed" , "See 12" , "Positive" , "Undoubtedly true" .)