Transvestite's undergarment? (4)

I believe the answer is:

vest

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

'undergarment?' is the definition.
(I know that vest is a type of undergarment)

'transvestite's' is the wordplay.
'VEST' is hidden in amongst the letters.
However, I'm not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for vest that I've seen before include "Undershirt, singlet" , "Sleeveless garment" , "Undergarment covering trunk of body" , "An American man's waistcoat" , "Upper undergarment, singlet" .)

I've seen this clue in The Telegraph.

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.