You are caught entering young man's office (6)
I believe the answer is:
bureau
'office' is the definition.
('bureau' can be a synonym of 'office')
'you are caught entering young man's' is the wordplay.
'you' becomes 'u' (I've seen this in other clues).
'are caught' becomes 'r' (I can't justify this - if you can you should give a lot more credence to this answer).
'entering' indicates putting letters inside.
'young man' becomes 'beau' ('beau' can be a synonym of 'young man').
'u'+'r'='ur'
'ur' going inside 'beau' is 'BUREAU'.
(Other definitions for bureau that I've seen before include "Item of furniture" , "Agency - writing desk" , "Writing desk with drawers" , "The ------, familiar name of the FBI" , "The B in the FBI" .)