Opener Britney Cooper (39 from 33 balls) top scored for the Windies, but when she was run out in unfortunate circumstances, the rot set in.

Cooper was backing up too far at the non-striker's end when right-arm spinner Gardner, bowling around the wicket, got a fingertip to a straight drive by Stacy-Ann King that crashed into the stumps.

A horrible mix-up resulted in the run out of Natasha McLean, who hadn't faced a delivery, while Sheneta Grimmond (five) was also run out as the Windies slumped from 2-55 to 7-64 within three overs.

Only some late resistance from Chinelle Henry (21no) and Shabika Gajnabi (11) got the Windies close to the century mark as eight batters failed to reach double figures.

Healy lost opening partner Beth Mooney (eight) in the sixth over of the chase, with the score on 44, but Lanning's 22 not out helped Australia ease to another dominant win.

The final match of the T20 series is on Thursday (AEST) at Kensington Oval, with Australia poised to complete a tour clean sweep having won the opener by six wickets after they wrapped up the ODI series 3-0 last week.

AAP