What is the meaning of idiom to doctor wine?

Here's a breakdown:

* "Doctor" in this context refers to the act of altering or manipulating something.

* "Wine" is the substance being altered.

The things added to wine to "doctor" it can include:

* Sugar: to make it sweeter

* Water: to dilute it

* Coloring: to make it appear more appealing

* Artificial flavors: to mask undesirable tastes

* Chemicals: to preserve it or enhance its appearance

Examples:

* "The restaurant was caught doctoring their wine by adding cheap red wine to their more expensive bottle."

* "Some unscrupulous winemakers doctor their wine with sugar to hide its flaws."

Essentially, "to doctor wine" implies a deceptive practice meant to mislead customers or consumers about the quality of the wine.