Courts of record formerly backed trustworthiness (5)
I believe the answer is:
steel
'courts of record' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for steel that I've seen before include "brace" , "Strong metal" , "Hard, strong, grey alloy" , "Strength, determination" , "Structural metal alloy" .)