Answer:

deepens

Answer	Crossword Clue
DEEPENS	Gets more profound
DEEPENS	Increases in intensity, as a storm
DEEPENS	Strengthens

DEEPENS	Digs down further
DEEPENS	Becomes less shallow
DEEPENS	Compounds, as a mystery
DEEPENS	Gets lower
DEEPENS	Intensifies
DEEPENS	Becomes more intense
DEEPENS	Gets stronger
DEEPENS	Digs farther down

DEEPENS	Becomes more profound
DEEPENS	Excavates further
DEEPENS	Falls more
DEEPENS	Extends farther down
DEEPENS	Gets more complicated
DEEPENS	Dredges.
DEEPENS	Intensifies.
DEEPENS	Becomes more complicated.

DEEPENS	Becomes more complex.
DEEPENS	Becomes more profound.
DEEPENS	Reams.
DEEPENS	Becomes intense.
DEEPENS	Darkens, as a color.
DEEPENS	Becomes darker.
DEEPENS	Becomes profound
DEEPENS	Dredges

DEEPENS	Gets more interesting, say
DEEPENS	Goes lower
DEEPENS	Grows more intense
DEEPENS	Increases in intensity