Is such a diet rich in iron? (6)
I believe the answer is:
staple
'iron?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for staple that I've seen before include "Fasten with short U-shaped bits of wire" , "Basic element" , "Paper pin for plates" , "The food one normally eats" , "Paper fastener found on plates" .)