True, it's a molten alloy (5)
I believe the answer is:
loyal
'true' is the definition.
(I've seen this before)
'a molten alloy' is the wordplay.
'a molten' is an anagram indicator (I've seen this in other clues).
'alloy' anagrammed gives 'LOYAL'.
'it's' is the link.
(Other definitions for loyal that I've seen before include "Faithful to country, cause or friend" , "Alloy (anag.)" , "Faithful (in allegiance)" , "Sort of toast" , "Showing enduring firm support" .)