Essential parts or pieces dipped in molten steel (8)
I believe the answer is:
elements
'essential parts' is the definition.
'elements' can be an answer for 'parts' (element is a kind of part). I am not certain of the 'essential' bit.
'pieces dipped in molten steel' is the wordplay.
'pieces' becomes 'men' (man can mean a chess piece).
'dipped in' means one lot of letters goes inside another.
'molten' indicates an anagram (I've seen this in other clues).
'steel' with letters rearranged gives 'elets'.
'men' placed into 'elets' is 'ELEMENTS'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for elements that I've seen before include "Rudiments of a subject" , "Constituents, ingredients" , "He and I are two" , "Components or weather conditions" , "Constituent parts or weather conditions" .)