Select the INCORRECTLY spelt word…

The correct answer is Reciept.

Let us analyze the spelling of each option to identify the incorrectly spelt word:
1. Irritate: Correctly spelt. It means to annoy or make someone slightly angry.
2. Necessitate: Correctly spelt. It means to make something necessary as a result or consequence.
3. Reciept: Incorrectly spelt. The correct spelling is Receipt. According to the common English spelling rule "i before e except after c" (when the sound is a long "ee"), the letter 'e' should come before 'i' because it follows the letter 'c'. A receipt is a written acknowledgment that something of value has been received.
4. Hindrance: Correctly spelt. It means a thing that provides resistance, delay, or obstruction to something or someone.

Therefore, the incorrectly spelt word among the given options is "Reciept".