Trainee model nude in Times, following Sun (7)
I believe the answer is:
student
'trainee' is the definition.
(I've seen this before)
'model nude in times following sun' is the wordplay.
'model' indicates anagramming the letters.
'in' indicates putting letters inside.
'times' becomes 'tt' (two abbreviations for time).
'following' is a charade indicator (letters next to each other).
'sun' becomes 's'.
'nude' anagrammed gives 'uden'.
'uden' going inside 'tt' is 'tudent'.
'tudent' after 's' is 'STUDENT'.
(Other definitions for student that I've seen before include "Scholar" , "One at university" , "University attendee" , "Undergraduate maybe" , "A learner as at school" .)