Element found by Zulu in chapter (4)
I believe the answer is:
zinc
'element' is the definition.
(zinc is a kind of element)
'by zulu in chapter' is the wordplay.
'by' means one lot of letters go next to another.
'zulu' becomes 'z' (phonetic alphabet: alpha, bravo, charlie etc.).
'chapter' becomes 'c'.
'z' put next to 'in' is 'zin'.
'zin'+'c'='ZINC'
'found' acts as a link.
(Other definitions for zinc that I've seen before include "Metallic element present with copper in brass" , "Metal, Zn" , "Blue-white metal" , "Constituent of brass" , "Mineral" .)