The rain in Spain? Crossword Clue

 The answer to the crossword clue "The rain in Spain?" is AGUA. It is a Spanish word that means "water". The clue is a reference to the song "My Fair Lady", in which the character Eliza Doolittle sings about how the rain in Spain stays mainly in the plain.

Here are some other possible answers to the clue "The rain in Spain?":

AGUA

LLUVIA

PRECIPITACIÓN

AGUACIL

NUBE

TORMENTA

I hope this helps!