Militant Catalan, if badly treated (9)

I believe the answer is:

fanatical

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'militant' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?

'catalan if badly treated' is the wordplay.
'badly treated' indicates an anagram.
'catalan'+'if'='catalanif'
'catalanif' anagrammed gives 'FANATICAL'.

Can you help me to learn more?

(Other definitions for fanatical that I've seen before include "Over-zealous" , "Excessively zealous" , "Obsessive" , "Unreasonably zealous" , "Mad" .)

I've seen this clue in the Sydney Morning Herald.

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