Thief who enters a building to steal (7)
I believe the answer is:
burglar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thief who enters a building to steal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for burglar that I've seen before include "Intruder with intent to steal" , "A stealer from homes" , "House robber" , "One breaking in" , "Building robber" .)