Crossword Clue:

to combine chemically with water

AnswerCrossword Clue
HYDRATECombine with water.
INERTHard to combine, chemically
SMOKEWord that can combine with the starts of the answers to the six starred clues
FIREWord that can combine with the ends of the answers to the six starred clues
THINSAdds water to, with "out"