Novice has shower in shirt (7)
I believe the answer is:
trainee
'novice' is the definition.
(I know that trainee is a type of novice)
'shower in shirt' is the wordplay.
'shower' becomes 'rain' (synonyms).
'in' indicates putting letters inside.
'shirt' becomes 'tee shirt' (tee shirt is a kind of shirt).
'rain' placed into 'tee' is 'TRAINEE'.
'has' acts as a link.
(Other definitions for trainee that I've seen before include "Apprentice" , "21 [TYRO]" , "Person being taught" , "one needs to practice" , "encountered bad weather in driving area" .)