Make the square into an octagon and do it the easy way (3,7)
I believe the answer is:
cut corners
'an octagon and do it the easy way' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'make the square' is the wordplay.
'make' becomes 'cut' (cutting is a kind of making).
'the square' becomes 'corners' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'cut'+'corners'='CUT CORNERS'
'into' acts as a link.
Can you help me to learn more?
(Other definitions for cut corners that I've seen before include "Skimp on effort" , "Miss out things to save money" .)