The odds are the crumpled note contains another crumpled note (3,2,3)
I believe the answer is:
ten to one
'the odds are' is the definition.
The definition suggests a singular noun which matches the answer.
'crumpled note contains another crumpled note' is the wordplay.
'crumpled' indicates an anagram (a crumbled or damaged version of the letters).
'contains' indicates putting letters inside.
'another crumpled note' becomes 'ento' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'note' with letters rearranged gives 'tone'.
'tone' enclosing 'ento' is 'TEN-TO-ONE'.
'the' is the link.
Can you help me to learn more?
(Other definitions for ten to one that I've seen before include "Most likely" , "In all probability" , "time?" .)