A great figure, just to put the icing on the cake! (3,2,3)
I believe the answer is:
cap it all
'a great figure just to put the icing on the cake' is the definition.
I know nothing about this answer so I can't tell whether this works.
'great figure just to put the icing on the cake' is the wordplay.
I cannot really see how this works, but
'great' could be 'capital' (synonyms) and 'capital' is located in the answer.
'figure' could be 'l' (I've seen this in other clues) and 'l' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cap it all that I've seen before include "Climax" , "Surpass or outdo something" .)