Get away, carrying diamonds after a stunt (8)
I believe the answer is:
escapade
'stunt' is the definition.
(I've seen this before)
'get away carrying diamonds after a' is the wordplay.
'get away' becomes 'escape' ('escape' can be a synonym of 'get away'**).
'carrying' is an insertion indicator.
'diamonds' becomes 'd' (abbreviation in bridge say).
'after' means one lot of letters go next to another.
'd' after 'a' is 'ad'.
'escape' enclosing 'ad' is 'ESCAPADE'.
(Other definitions for escapade that I've seen before include "Madcap adventure" , "daring exploit" , "Wild adventure" , "Exciting, perhaps mischievous, adventure" , "Risky venture" .)