Criticise after loss of airline that hurts Chicago? (4)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

[ba] SH (slang for criticise harshly) without BA (abbreviation for British Airways = airline), then OW (that hurts!). Definition by example: Chicago is a 1970s stage musical (show), based on a 1920s play.