Figure skater's last elegant performance bags 100 (9)
I believe the answer is:
rectangle
'figure' is the definition.
(rectangle is a kind of figure)
'skater's last elegant performance bags 100' is the wordplay.
'last' says to take the final letters.
'performance' is an anagram indicator.
'bags' indicates putting letters inside (bag can mean secures or steals).
'100' becomes 'c' ('C' can be a synonym of '100').
The last letter of 'skater' is 'r'.
'r'+'elegant'='relegant'
'relegant' anagrammed gives 'retangle'.
'retangle' placed around 'c' is 'RECTANGLE'.
(Other definitions for rectangle that I've seen before include "Parallelogram with four right angles" , "Quadrilateral" , "Geometric figure with four right angles, not square" , "box" , "Four-sided figure" .)