Be under someone's thumb
Keep an eye on
Smell something fishy
Turn a blind eye
Smell a rat
Bury your head in the sand
Let the cat out of the bag
Give the green light
Gain (or have) the upper hand
Pull a few strings
Give permission
Ignore a situation
To sense something is wrong
to reveal a secret
be controlled by someone else
to be suspicious
to not take notice of something
Watch over
take advantage of something
to use your influence to your own advantage