I'm wrong to rant and rave at a mere illusion (6)

I believe the answer is:

mirage

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

'a mere illusion' is the definition.
'mirage' can be an answer for 'illusion' (I've seen this before). I'm unsure of the 'a mere' bit.

'i'm wrong to rant and rave' is the wordplay.
'wrong' indicates an anagram.
'to rant and rave' becomes 'rage' (I've seen this in another clue).
'im' is an anagram of 'mi'.
'mi'+'rage'='MIRAGE'

'at' acts as a link.

Can you help me to learn more?

(Other definitions for mirage that I've seen before include "Something illusory and unattainable" , "Illusory image" , "fantasy" , "image, not what it seems" , "You might see this in desert" .)

I've seen this clue in the Evening Standard.

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