Distrustful (10)
(Other definitions for suspicious that I've seen before include "Dodgy" , "Shady; untrusting" , "open to doubt" , "questionable" , "Showing distrust" .)
'distrustful' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for leery that I've seen before include "Cautious due to suspicions" , "Shy" , "Knowing" , "Suspiciously cautious" , "Cunning - wary" .)