Rearing bats with greater spleen? (7)

I believe the answer is:

angrier

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'greater spleen?' is the definition.
The answer and definition are not the same part of speech.

'rearing bats' is the wordplay.
'bats' is an anagram indicator (slang for mad).
'rearing' is an anagram of 'ANGRIER'.

'with' is the link.

Can you help me to learn more?

(Other definitions for angrier that I've seen before include "More irate" , "More annoyed" , "More worked up" , "Not so calm" , "More furious" .)

I've seen this clue in The Guardian.

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