More suspicious and give a sly look. That’s right! (7)
I believe the answer is:
leerier
'more suspicious' is the definition.
('leery' can be a synonym of 'suspicious')
'give a sly look that's right' is the wordplay.
'give' says to put letters next to each other.
'a sly look' becomes 'leer' (I've seen this before).
'that's' becomes 'ie'.
'right' becomes 'r' (common abbreviation).
'leer' put next to 'ie' is 'leerie'.
'leerie'+'r'='LEERIER'
'and' acts as a link.
(Other definitions for leerier that I've seen before include "more wary" , "more cunning" .)