Buyer swindles you and me on tenth anniversary (8)
I believe the answer is:
consumer
'buyer' is the definition.
(I have seen 'Buyer of goods' mean 'consumer' so perhaps 'buyer' could also mean 'consumer')
'swindles you and me on tenth anniversary' is the wordplay.
'swindles' becomes 'cons' (con is a kind of swindle).
'you' becomes 'u' (homophones).
'and' says to put letters next to each other.
'me on tenth anniversary' becomes 'mer' (I can't explain this - if you can you should give a lot more credence to this answer).
'cons'+'u'+'mer'='CONSUMER'
Can you help me to learn more?
(Other definitions for consumer that I've seen before include "one may be looking for the product" , "Buyer of goods" , "Person who buys goods or service" , "One buying goods" , "Client" .)