A bed of nails

An extremely difficult situation or existence.

A bitter pill to swallow

Something that is difficult or painful to accept.

A bit much

If something is excessive or annoying, it is a bit much.

A case in point

Relevant example.

Ace in the hole

An ace in the hole is something other people are not aware of that can be   used to your advantage when the time is right.

A cut above

Somebody or something superior to somebody or something.

A dime a dozen

Anything that is common and easy to get.

A dog’s life

A wretched existence.

A done deal

Something that has already been settled or finalized.

A drop in the bucket

A very small part of something big or whole.

A labor of love

Demanding or difficult that is done just for pleasure rather than for money.

A lapse from grace

Failure in moral conduct or religious belief.

A leap in the dark

An action taken without knowing what the outcome or consequences will be.

A load off your mind

Relief from anxiety or worry.

A lick and a promise
   

If you give something a lick and a promise, you do it hurriedly, most often incompletely, intending to return to it later.

A long row to hoe

Something that is a long row to hoe is a difficult task that takes a long time.

A lost ball in the high weeds
.

A lost ball in the high weeds is someone who does not know what they are doing, where they are or how to do something

A man of his word

Somebody who keeps his promise.

A matter of opinion

A subject about which there are varying views.

A mouth to feed

Somebody who must be provided for, especially fed.

A new lease on life

Renewed freshness or vigor, usually resulting from some minor change.

A pain in the neck

Somebody that is considered extremely annoying or troublesome.

A piece of cake

A task that can be accomplished very easily.

A place in the sun

Position of success, happiness, or prosperity.

A slap on the wrist

A very mild punishment.

A shot in the arm

Something that has a sudden good effect on somebody or something.

A shot in the dark
   

A guess made without any information, an attempt made in desperation but with little hope of success.

A skeleton in the closet

A closely kept secret that is a source of shame or embarrassment.

A snake in the grass

An offensive term for somebody perceived as betraying or deceiving others.

A straw in the wind

A relatively minor incident or thing that gives some indication  of what is likely to happen in  the future.

A penny for your thoughts

This idiom is used as a way of asking someone what they are thinking   about.

A penny saved is a penny earned

This means that we shouldn’t spend or waste money, but try to save it.

A picture is worth a thousand words

A picture can often get a message across much  better than the best verbal description

A problem shared is a problem halved

If you talk about your problems, it will make you feel better.

A still tongue keeps a wise head

Wise people don’t talk much.

At a loss

If you are at a loss, you are unable to understand or comply

At a snail’s pace

If something moves at a snail’s pace, it moves very slowly.

At every turn

Everywhere, or at every significant moment.