Yes, CRAWLER is a Scrabble word!

Letter values in Scrabble US: C 3, R 1, A 1, W 4, L 1, E 1, R 1.

Is it a valid word?

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

a person who tries to please someone in order to gain a personal advantage
a person who crawls or creeps along the ground
terrestrial worm that burrows into and helps aerate soil; often surfaces when the ground is cool or wet; used as bait by anglers

Also: ass-kisser, fishing worm, dew worm, red worm.

Not playable in Scrabble US: NIGHTCRAWLER.