Give terrible review about one worse on stage (7)

I believe the answer is:

hammier

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

'give terrible review about' is the definition.
I can't judge whether this defines the answer.

'one worse on stage' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
The remaining letters 'hammer' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Times.

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.