A number four iron brought out (4)
I believe the answer is:
five
'a number' is the definition.
(five is a kind of number)
'four iron brought out' is the wordplay.
I cannot quite see how this works, but
'four' could be 'iv' (Roman numerals) and 'iv' is located in the answer.
'iron' could be 'fe' (Fe is the chemical symbol for iron) and 'fe' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for five that I've seen before include "Quintet" , "Prime number" , "Odd number" , "Top-quality hotel has these stars" , "Fourth part of score" .)