Metal in Cadiz, incinerated (4)
I believe the answer is:
zinc
'metal' is the definition.
(zinc is a kind of metal)
'in cadiz incinerated' is the wordplay.
'in' says the answer is hidden in the clue.
'ZINC' can be found hidden inside 'cadiz incinerated'.
(Other definitions for zinc that I've seen before include "Galvanizing metal" , "Silvery-white metal" , "Antioxidant element" , "Metal much used in alloys" , "Constituent of brass" .)