A female airline hostess (crew), who is a bit beyond her use-by-date, and loves hunting for younger men in a similar manner as a cougar.
Crew-gars often hang out in hotel bars - hotels where they are staying overnight on long haul flights. They will usually hang out with other crew-gars and not associate with younger crew members.
Being airline crew they are used to looking after themselves and usually dress well.
Example of the word in use:
Male 1: "Hey - check out the older ladies on the other side of the bar".
Male 2: "Careful mate - they look like crew-gars"