The most common and most likely answer to this crossword clue is the 5 letter word FILCH
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Buddy explains!
The straight part
We know that "Rob" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rob = filch.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does FILCH mean?
FILCH noun- Something which has been filched or stolen.
- An act of filching; larceny, theft.
- A person who filches; a filcher, a pilferer, a thief.
- A hooked stick used to filch objects.
- To illegally take possession of (especially items of low value); to pilfer, to steal.