Figure of old Charlie — with label attached (7)
I believe the answer is:
octagon
'figure' is the definition.
(type of geometrical figure)
'old charlie with label attached' is the wordplay.
'old charlie' becomes 'oc' (this might be a standard abbreviation I've not previously seen).
'with' means one lot of letters go next to another.
'label' becomes 'tag' (synonyms).
'attached' becomes 'on' (I've seen this in other clues).
'oc'+'tag'+'on'='OCTAGON'
'of' is the link.
Can you help me to learn more?
(Other definitions for octagon that I've seen before include "plane figure" , "Figure with 8 sides" , "with eight angles" , "Eight-sided figure" , "regular form" .)