Hand

OK, here are a few idioms, all containing the word 'hand'.

hand in glove British, American & Australian, American hand and glove

if one person or organization is working hand in glove with another, they are working together, often to do something dishonest 
It was rumoured at the time that some of the gangs were working hand in glove with the police.

bite the hand that feeds you

to treat someone badly who has helped you in some way, often someone who has provided you with money 
Leaving the company after they've spent three years training you up - it's a bit like biting     the hand that feeds you.

show your hand

to tell people your plans or ideas, especially if you were keeping them secret before 
When card players show their hand in a game of cards, they show the other players the cards they are holding, usually because they cannot continue to play the game.
I'm a bit reluctant to show my hand at this stage in the proceedings.

wait on sb hand and foot

to do everything for someone so that they do not have to do anything for themselves 
He just wants a woman to wait on him hand and foot.

an old hand

someone who has done a particular job or activity for a long time and who can do it very well 
She's an old hand at magazines, having trained on Cosmopolitan before editing Company. [often + at]

(from Cambridge International Dictionary of Idioms)