Single line for loop over iterator with an "if" filter?

You could do:

for airport in filter(lambda x: x.is_important, airports):
    # do stuff...

No, there is no shorter way. Usually, you will even break it into two lines :

important_airports = (airport for airport in airports if airport.is_important)
for airport in important_airports:
    # do stuff

This is more flexible, easier to read and still don't consume much memory.