Hey Derek! Make an off-peak call? (5)

I believe the answer is:

yodel

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

'peak call?' is the definition.
(I've seen this in another clue)

I don't understand the remainder of the clue.

(Other definitions for yodel that I've seen before include "Vocalise" , "Sing in high pitch like Swiss mountain dwellers" , "Sing by alternating between normal voice and falsetto" , "Sing in Tyrolean fashion" , "Loftily call" .)

I've seen this clue in The Telegraph and The Sun.

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.