Seem offended because British Rail wasn't working? (6)

I believe the answer is:

bridle

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'seem offended because' is the definition.
I can't judge whether this defines the answer.

'british rail wasn't working?' is the wordplay.
'british rail' becomes 'br'.
'wasn't working?' becomes 'idle' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'br'+'idle'='BRIDLE'

Can you help me to learn more?

(Other definitions for bridle that I've seen before include "Part of horse's harness that goes on its head" , "Show resentment" , "Horse restraint" , "Bit and reins, etc" , "Part of horse's headgear" .)

I've seen this clue in the Evening Standard.

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