> ## Documentation Index
> Fetch the complete documentation index at: https://docs.automate.ax/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Automate.ax automations are TypeScript programs.
> Use Bun for installation and command examples.
> Use Automate.ax for the product name and automate.ax for the package, CLI, and domain.
> Treat documented public APIs as current; do not invent transitional or deprecated names.

# Clear card Custom Field value

> Clear one Custom Field value from a Trello card.

`trello.clearCardCustomFieldValue` removes one populated value from a card without deleting the field definition.

```ts automations/clear-trello-card-custom-field-value.automation.ts theme={null}
import { automation, onDashboardRun } from "automate.ax"
import { trello } from "automate.ax/trello"

export default automation("Clear Trello card estimate", () => {
  onDashboardRun({ title: "Clear Trello card estimate" })
  trello.clearCardCustomFieldValue({
    card: "card-id",
    customFieldId: "custom-field-id",
  })
})
```

Provide `card` as an ID, short link, or standard card URL and a stable `customFieldId`. Optional second argument `{ account }` selects a Trello binding.

Returns `Signal<{ cardId: string; cleared: true; customFieldId: string }>`.