Prepare (oneself) (5)
(Other definitions for steel that I've seen before include "Mixture of carbon and iron" , "nerve" , "Determination, metal" , "Strong metal" , "Structural metal alloy" .)
'prepare oneself' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for get ready that I've seen before include "third of three" , "Prepare oneself" .)