Be successful with peg that's left behind (2,4)
I believe the answer is:
do well
'be successful' is the definition.
I can't tell whether this definition defines the answer.
'peg that's left behind' is the wordplay.
'peg' becomes 'dowel' (a dowel is a wooden peg).
'that's left' becomes 'l' (common abbreviation).
'behind' is a charade indicator (letters next to each other).
'dowel'+'l'='DO WELL'
'with' is the link.
Can you help me to learn more?
(Other definitions for do well that I've seen before include "Flourish" , "boom" .)