Marauders; horsemen surrounding area (7)
I believe the answer is:
'marauders' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for raiders that I've seen before include "Marauders" , "Attacking force" , "' - - of the Lost Ark'" , "Marauding attackers" .)