Armour that’s important to protect leg essentially (6)
I believe the answer is:
greave
'armour' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for greave that I've seen before include "Leg armour" , "shin guard" .)