Dallas clan say embodies success (5)
I believe the answer is:
ewing
'dallas clan' is the definition.
(I've seen this in another clue)
'say embodies success' is the wordplay.
'say' becomes 'eg' (both can mean 'for example').
'embodies' is an insertion indicator.
'success' becomes 'win' (I've seen this in another clue).
'eg' placed around 'win' is 'EWING'.
(Other definitions for ewing that I've seen before include "Oil family" , "Fictional oil baron" .)