Yes, GIRDLING is a Scrabble word!

Letter values in Scrabble US: G 2, I 1, R 1, D 2, L 1, I 1, N 1, G 2.

Is it a valid word?

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

cut a girdle around so as to kill by interrupting the circulation of water and nutrients
put a girdle on or around