In the middle of tsunami, considered it to be serious (8)

I believe the answer is:

unamused

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'be serious' is the definition.
(I've seen this before)

'in the middle of tsunami considered' is the wordplay.
'in the middle of' indicates the central letters (I've seen 'in the middle' mean this).
'considered' becomes 'mused' (I can't justify this - if you can you should give a lot more credence to this answer).
The central letters of 'tsunami' are 'una'.
'una'+'mused'='UNAMUSED'

'it to' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for unamused that I've seen before include "Not finding things funny" , "Not entertained" , "like Queen Victoria" , "Serious" .)

I've seen this clue in The Irish Times.

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