Topless trespasser is high-value target (5)

I believe the answer is:

inner

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'target' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for inner that I've seen before include "Located inside" , "Exclusive to a center" , "Good shot at archery" , "Opposite of outer" , "Deep" .)

I've seen this clue in The Sun.

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