Players' money belts (5,5)
I believe the answer is:
brass bands
'players' money belts' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.
'money belts' is the wordplay.
'money' becomes 'brass' (brass can informally mean money).
'belts' becomes 'bands' (I can't explain this - if you can you should give a lot more credence to this answer).
'brass'+'bands'='BRASS BANDS'
Can you help me to learn more?
(Another definition for brass bands that I've seen is " Groups of musicians".)