Beautiful creation Pisan admits is leaning to one side (8)
I believe the answer is:
partisan
'leaning to one side' is the definition.
I can't judge whether this defines the answer.
'beautiful creation pisan admits' is the wordplay.
'beautiful creation' becomes 'art' (art is a kind of creation. I am not sure about the 'beautiful' bit.).
'admits' means one lot of letters goes inside another.
'art' inserted within 'pisan' is 'PARTISAN'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for partisan that I've seen before include "Traps in a prejudiced way" , "In Sparta (anag)" , "Enthusiastic supporter" , "Blindly loyal to one side" , "Prejudiced towards one cause" .)