Student taking shower in slip-on garment (7)

I believe the answer is:

trainee

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

'student' is the definition.
(I've seen this before)

'shower in slip-on garment' is the wordplay.
'shower' becomes 'rain' (rainfall).
'in' indicates putting letters inside.
'slip on garment' becomes 'tee' (I can't explain this - if you can you should believe this answer much more).
'rain' inserted inside 'tee' is 'TRAINEE'.

'taking' is the link.

Can you help me to learn more?

(Other definitions for trainee that I've seen before include "Person being instructed in work" , "Aintree (anag.)" , "one needs to practice" , "Student" , "21 [TYRO]" .)

I've seen this clue in The Times.

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.