Trusty defender's broken law, interrupting kick-off (8)

I believe the answer is:

stalwart

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'trusty defender's' is the definition.
'stalwart' can be an answer for 'defender's' (thesaurus). I am not sure about the 'trusty' bit.

'broken law interrupting kick-off' is the wordplay.
'broken' is an anagram indicator.
'interrupting' indicates putting letters inside.
'kick off' becomes 'start' (start of a football match).
'law' is an anagram of 'alw'.
'alw' going inside 'start' is 'STALWART'.

Can you help me to learn more?

(Other definitions for stalwart that I've seen before include "Loyal supporter" , "husky" , "Resolute and firm" , "Valiant" , "Loyal figure" .)

I've seen this clue in The Independent.

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