Yes, EAGRE is a Scrabble word!

Letter values in Scrabble US: E 1, A 1, G 2, R 1, E 1.

Is it a valid word?

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

a high wave (often dangerous) caused by tidal flow (as by colliding tidal currents or in a narrow estuary)

Also: tidal bore.

Not playable in Scrabble US: AEGIR.