Ava mustered every ___ in her brain Crossword Clue

 The answer to the crossword clue "Ava mustered every ___ in her brain" is NEURON. This is a 6-letter word that refers to a nerve cell.

In the context of the clue, Ava is mustering all of her brainpower to come up with a witty or clever response to Dana's compliment. She is trying to impress Dana and show her that she is interested in her.

The word "neuron" is a play on the word "new." Ava is trying to come up with a new and creative way to respond to Dana.

I hope this helps!