Spongy stomach muscles - alternatively crooked (9)
I believe the answer is:
absorbent
'spongy' is the definition.
(similar in meaning)
'stomach muscles alternatively crooked' is the wordplay.
'stomach muscles' becomes 'abs' (abdominal muscles).
'alternatively' becomes 'or'.
'crooked' becomes 'bent' (both can mean corrupt).
'abs'+'or'+'bent'='ABSORBENT'
(Other definitions for absorbent that I've seen before include "Able to soak up moisture" , "able to soak in the sun?" , "Able to mop up" , "receptive" , "Such material is able to take in water" .)