Crossword Genius

Fly from trenches in retreat (5)

Ross

I believe the answer is:

speed

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

'fly' is the definition.
(thesaurus)

'from trenches in retreat' is the wordplay.
I cannot quite see how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is found in the answer.
The remaining letters 'sped' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for speed that I've seen before include "Swiftness" , "Move quickly (and illegally?)" , "Rapidity of movement" , "Rate of progress" , "Film sensitivity to light" .)

I've seen this clue in The 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.