Cast in flop aspires to get art therapy (7,2,5)
I believe the answer is:
plaster of paris
'cast' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for plaster of paris that I've seen before include "What might make cast" , "material for cast" , "is needed for the cast?" .)