Unpleasant shower drink after tai-chi oddly cancelled (4,4)

I believe the answer is:

acid rain

I'm a little stuck... Click here to teach me more about this clue!

'drink after tai-chi oddly cancelled' is the definition.
I can't judge whether this definition defines the answer.

'unpleasant shower' is the wordplay.
'unpleasant' becomes 'acid' (similar in meaning).
'shower' becomes 'rain' (rainfall).
'acid'+'rain'='ACID-RAIN'

Can you help me to learn more?

(Other definitions for acid rain that I've seen before include "Harmful drops" , "environmental disaster" , "it's bad for the environment" , "that pollutes" , "Dangerous precipitation" .)

I've seen this clue in The Independent.

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