Crossword Genius

Writer of Morse inserting line that's not so friendly (6)

Ross

I believe the answer is:

colder

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

'not so friendly' is the definition.
(cold can mean unfriendly or distant)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for colder that I've seen before include "Less warm" , "Of a lower temperature" , "More nippy" , "Not so hot" .)

I've seen this clue in The Guardian.
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.