The answer to the crossword is CEREBRA, which is a reference to the fictional character Cerebra from Marvel Comics. Cerebra is a powerful computer created by Professor Charles Xavier to help the X-Men in their fight against evil mutants. It is capable of thinking and analyzing data quickly, making it an invaluable asset to the team. In essence, Cerebra can be said to 'do the thinking' for the X-Men, which is why it is the answer to the crossword clue.