Wrought steel is an absolute requirement (9)
I believe the answer is:
essential
'absolute requirement' is the definition.
(something essential)
'wrought steel is an' is the wordplay.
'wrought' indicates an anagram (I've seen this in other clues).
'steel'+'is'+'an'='steelisan'
'steelisan' with letters rearranged gives 'ESSENTIAL'.
(Other definitions for essential that I've seen before include "Vitally important" , "Indispensible" , "Type of oil" , "Indispensable, necessary" , "as oil might be" .)