From Oxford dictionary I have the first sentence. But from my grammar book is the following quote: "When the future event doesn't depend on the action described in the if-clause, we use be going to, not will." So, is it not better to use "will" in this example because there is a need for a clue?
I'm never going to guess the answer if you don't give me a clue.
I will never guess the answer if you don't give me a clue.