Grill people lining up for a haircut, we're told? (8)
I believe the answer is:
barbecue
'grill' is the definition.
(barbecuing is a kind of grilling)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for barbecue that I've seen before include "garden party" , "Meal outdoors cooked on a grill" , "Portable grill for cooking outdoors" , "Open-air party with roast meats etc" , "Cuba beer (anag.)" .)