Sorry some trucks need different fuel (6)

I believe the answer is:

rueful

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'sorry' is the definition.
(synonyms)

'some trucks need different fuel' is the wordplay.
'some trucks need' becomes 'ru' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'different' indicates anagramming the letters.
'fuel' is an anagram of 'eful'.
'ru'+'eful'='RUEFUL'

Can you help me to learn more?

(Other definitions for rueful that I've seen before include "Repentant" , "'Contrite, remorseful (6)'" , "Regretting" , "Apologetic" , "In a sorry state!" .)

I've seen this clue in the Evening Standard.

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