A limit to hardened English army (5)

I believe the answer is:

horde

I'm a little stuck... Click here to teach me more about this clue!

'army' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for horde that I've seen before include "Vast crowd" , "Huge noisy crowd" , "Nomadic army" , "Throng, mass" , "Vast multitude" .)

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app