Select the INCORRECTLY spelt word.

The correct answer is cabagge.

To find the incorrectly spelt word, let us examine each of the given options:
1. receipt: This spelling is correct. It refers to a written acknowledgment that a specified article or sum of money has been received.
2. privilege: This spelling is correct. It refers to a special right, advantage, or immunity granted or available only to a particular person or group.
3. awkward: This spelling is correct. It means causing or feeling embarrassed or inconvenient.
4. cabagge: This spelling is incorrect. The correct spelling is cabbage (c-a-b-b-a-g-e), which is a cultivated plant consumed as a vegetable. The incorrect spelling swaps the double 'b' for a double 'g'.

Therefore, the incorrectly spelt word is cabagge.