Our steel turned firm (8)
I believe the answer is:
resolute
'firm' is the definition.
(similar in meaning)
'our steel turned' is the wordplay.
'turned' is an anagram indicator.
'our'+'steel'='oursteel'
'oursteel' is an anagram of 'RESOLUTE'.
(Other definitions for resolute that I've seen before include "Purposeful and unwavering" , "Admirably purposeful" , "without flinching" , "Determined, intent" , "'Firm, unhesitating (8)'" .)