Staying power of stonefish? (5)
I believe the answer is:
steel
'staying power' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for steel that I've seen before include "Structural metal alloy" , "Hard, strong, grey alloy" , "nerve" , "The staying power" , "Mixture of carbon and iron" .)