Short line of policemen? (3)
I believe the answer is:
met
'policemen?' is the definition.
(Metropolitan Police)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for met that I've seen before include "Came together, encountered" , "London police (abbr) - New York Museum of Art (abbr)" , "Encountered, came across" , "Encountered by chance or arrangement" , "Encountered, came into contact" .)