Yes, CLEANUP is a Scrabble word!

Letter values in Scrabble US: C 3, L 1, E 1, A 1, N 1, U 1, P 3.

Is it a valid word?

CLEANUP is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a very large profit
(baseball) the fourth position in the batting order (usually filled by the best batter on the team)
the act of making something clean

Also: cleanup position, cleanup spot.