Meaning of “sneaking” - Learner’s Dictionary

sneaking

adjective uk us /ˈsniːkɪŋ/
have a sneaking feeling/suspicion

to think that something is true but not be sure:

[ + (that) ] I have a sneaking feeling that the English test is going to be very difficult.
have a sneaking admiration/fondness for sb UK

to like someone secretly, especially when you do not want to

(Definition of “sneaking” from the Cambridge Learner’s Dictionary © Cambridge University Press)