Thank you, thank you again, and goodbye (2-2)
I believe the answer is:
ta-ta
'goodbye' is the definition.
(I've seen this before)
'thank you thank you again' is the wordplay.
I cannot quite see how this works, but
'thank you' could be 'ta' (informal way of saying thank you) and 'ta' is found within the answer.
The remaining letters 'ta' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for ta-ta that I've seen before include "Adieu" , "Bye-bye" , "Cheerio" , "A Farewell" , "Bye!" .)