Bidet is ordered with eccentric payment method (5,4)
I believe the answer is:
debit card
'payment method' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'bidet is ordered with eccentric' is the wordplay.
'is ordered' indicates an anagram.
'with' means one lot of letters go next to another.
'eccentric' becomes 'card' (card can mean an eccentric person).
'bidet' anagrammed gives 'debit'.
'debit'+'card'='DEBIT CARD'
Can you help me to learn more?
(Another definition for debit card that I've seen is " alternative to cash".)