Crossword Genius

Hard things to sharpen knives on? (6)

Ross

I believe the answer is:

steels

I'm a little stuck... Click here to teach me more about this clue!

'sharpen knives on?' is the definition.
I can't tell whether this defines the answer.

'hard things' is the wordplay.
'hard' becomes 'steel'.
'things' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'steel'+'s'='STEELS'

'to' is the link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.