Geometrically divided illustration, clean Mondrian boxes? (3,5)
I believe the answer is:
pie chart
'geometrically divided illustration' is the definition.
'pie chart' can be an answer for 'illustration' (pie chart is a kind of illustration). I'm not certain of the 'geometrically divided' bit.
'clean mondrian boxes?' is the wordplay.
'clean' becomes 'char' (char can mean a cleaner).
'mondrian' becomes 'Piet' (painter Piet Mondrian is an example).
'boxes?' is an insertion indicator (the outside letters must 'box' inside letters in).
'char' placed within 'piet' is 'PIE CHART'.
Can you help me to learn more?
(Other definitions for pie chart that I've seen before include "Display of data r" , "Circle divided by radii to depict percentages of the whole" , "Illustration of shares" , "Graph of a circle divided into sectors" , "Display of information" .)