Answer:

defiles

Answer	Crossword Clue
DEFILES	Makes dirty
DEFILES	Makes impure
DEFILES	Mountain passes.

DEFILES	Passes
DEFILES	Ravines' kin
DEFILES	Narrow passages
DEFILES	Corrupts

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.