The gateman has become a big business operator (7)

I believe the answer is:

magnate

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

'a big business operator' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'the gateman has' is the wordplay.
'gateman' anagrams to 'MAGNATE'.
But, I'm unsure how the anagram is indicated.

'become' acts as a link.

Can you help me to learn more?

(Other definitions for magnate that I've seen before include "Fellow with a lot of money" , "Tycoon" , "Baron" , "Fat cat" , "Wealthy figure" .)

I've seen this clue in The Irish Independent.

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.