Reform tries to react, sending those coming in away - certainly not my cup of tea! (9)

'reform' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I don't see?

'tries to react sending those coming in away certainly not my cup of tea' is the wordplay.
I cannot really see how this works, but
an anagram of 'tries' is 'istre' which is located in the answer.
'to' is present in the answer.
'tea' could be 't' (I've seen this in other clues) and 't' is found within the answer.
A single letter 'r' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?