Unofficial entrant! (7)

I believe the answer is:

burglar

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'unofficial entrant' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?

This is all the clue.

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(Other definitions for burglar that I've seen before include "Breaker and enterer?" , "One enters a building in order to steal" , "A criminal on one's premises" , "Thieving intruder" , "Thief who enters a building to steal" .)

I've seen this clue in the Evening Standard.

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