N symbol for a ship’s flag (6)

I believe the answer is:

ensign

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

'a ship's flag' is the definition.
(I've seen this before)

'n symbol' is the wordplay.
'n' becomes 'en' (I can't justify this - if you can you should believe this answer much more).
'symbol' becomes 'sign' (I've seen this in another clue).
'en'+'sign'='ENSIGN'

'for' acts as a link.

Can you help me to learn more?

(Other definitions for ensign that I've seen before include "Ship's colours" , "Flag - junior American naval officer" , "Flags flown by a ship to show its nationality" , "Flag - officer, formerly" , "SECOND PART OF 10" .)

I've seen this clue in the Sydney Morning Herald.

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.