give somebody an inch
US /ɡɪv ˈsʌm.bɑː.di ən ɪntʃ/
UK /ɡɪv ˈsʌm.bɑː.di ən ɪntʃ/
1.
to allow someone a small amount of freedom or advantage, which they then try to exploit to gain much more
:
•
If you give him an inch, he'll take a mile, so be firm with your boundaries.
•
My boss is very strict because he knows if he gives us an inch, we'll slack off.