Madman in range hits confused major (15)

I believe the answer is:

earthshattering

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

'madman in range hits confused major' is the definition.
I can't judge whether this definition defines the answer.

'madman in range hits confused' is the wordplay.
'madman' becomes 'hatter' (mad as a hatter).
'in' indicates putting letters inside.
'confused' indicates an anagram.
'range'+'hits'='rangehits'
'rangehits' anagrammed gives 'earthsing'.
'hatter' going into 'earthsing' is 'EARTHSHATTERING'.

Can you help me to learn more?

(Another definition for earthshattering that I've seen is " of great importance".)

I've seen this clue in The Daily Express.

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.