Post Office carries stolen picture (5)
I believe the answer is:
photo
'picture' is the definition.
(a photograph)
'post office carries stolen' is the wordplay.
'post office' becomes 'po'.
'carries' means one lot of letters goes inside another.
'stolen' becomes 'hot' (stolen goods are 'hot').
'po' enclosing 'hot' is 'PHOTO'.
(Other definitions for photo that I've seen before include "Snap, exposure, in short" , "Snap - shot" , "Picture, in short" , "In brief, a snapshot" , "Snap (abbrev.)" .)