Mail diminished carrying sexy snaps (6)
I believe the answer is:
photos
'snaps' is the definition.
(I've seen this before)
'mail diminished carrying sexy' is the wordplay.
'mail' becomes 'post' (synonyms).
'diminished' means to remove the last letter.
'carrying' indicates putting letters inside.
'sexy' becomes 'hot' (similar in meaning).
'post' with its last letter taken away is 'pos'.
'pos' enclosing 'hot' is 'PHOTOS'.
(Other definitions for photos that I've seen before include "Camera pictures" , "prints" , "Shots" , "snaps" , "In brief, snapshots" .)