Shifts if the robber appears (5)

I believe the answer is:

thief

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'robber appears' is the definition.
I can't tell whether this definition defines the answer.

'shifts if the' is the wordplay.
'shifts' is an anagram indicator.
'if'+'the'='ifthe'
'ifthe' anagrammed gives 'THIEF'.

Can you help me to learn more?

(Other definitions for thief that I've seen before include "Afternoon break" , "nicker?" , "He takes" , "One with taking ways" , "Crook" .)

I've seen this clue in the Sydney Morning Herald.

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