Justification for fighting bombast? (7)

I believe the answer is:

warrant

'justification' is the definition.

'fighting bombast?' is the wordplay.
'fighting' becomes 'war'.
'bombast?' becomes 'rant' (synonyms).
'war'+'rant'='WARRANT'

'for' is the link.

(Other definitions for warrant that I've seen before include "Justify; authorisation" , "Document giving authority" , "Permit for arrest, search of premises, etc" , "Merit, justify" , "Guarantee" .)

I've seen this clue in The Irish Independent.

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