On U-boat destroyed (5)

I believe the answer is:

about

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'on' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?

'u-boat destroyed' is the wordplay.
'destroyed' is an anagram indicator.
'u'+'boat'='uboat'
'uboat' is an anagram of 'ABOUT'.

Can you help me to learn more?

(Other definitions for about that I've seen before include "Concerned with" , "Apropos, concerning" , "nearby" , "round" , "Concerning or around" .)

I've seen this clue in The Sun.

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