Repetition of cheers for so long (2-2)
I believe the answer is:
ta ta
'so long' is the definition.
(both are ways of saying goodbye)
'repetition of cheers' is the wordplay.
I cannot quite understand how this works, but
'cheers' could be 'ta' (both can mean thank you) and 'ta' is present in 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...
'for' is the link.
Can you help me to learn more?
(Other definitions for ta ta that I've seen before include "Cheerio" , "Informal farewell or thank you" , "Bye-bye" , "Informal remark in farewell or gratitude" , "So long!" .)