To keep it trim, work out! (6)
I believe the answer is:
figure
'work out' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for figure that I've seen before include "movement by skater" , "Number; statue" , "Shape; number" , "Symbol, numeral" , "Build" .)