Finish off with an excellent left (3,2,3)
I believe the answer is:
cap it all
'finish' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'with an excellent left' is the wordplay.
'with' says to put letters next to each other.
'an excellent' becomes 'capital' (I've seen this before).
'left' becomes 'l' (common abbreviation).
'capital' put next to 'l' is 'CAP IT ALL'.
'off' is the link.
Can you help me to learn more?
(Other definitions for cap it all that I've seen before include "Surpass or outdo something" , "Climax" .)