Yes, FOCUSSED is a Scrabble word!

Letter values in Scrabble US: F 4, O 1, C 3, U 1, S 1, S 1, E 1, D 2.

Is it a valid word?

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

direct one's attention on something
cause to converge on or toward a central point
bring into focus or alignment; to converge or cause to converge; of ideas or emotions
become focussed or come into focus
put (an image) into focus; we cannot enjoy the movie"

Not playable in Scrabble US: CONCENTRE.