Staff catches one creep in high street (4,4)

I believe the answer is:

main drag

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

'street' is the definition.
(thesaurus)

'staff catches one creep in high' is the wordplay.
'staff' becomes 'man' (manning is a kind of staffing).
'catches' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'creep in high' becomes 'drag' (I can't justify this - if you can you should believe this answer much more).
'man' placed around 'i' is 'main'.
'main'+'drag'='MAIN DRAG'

Can you help me to learn more?

I've seen this clue in The Hindu.

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.