Entertainment district in London's West End (4)
I believe the answer is:
soho
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">entertainment district in london's west end</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 soho that I've seen before include "Central London entertainment district" , "London's nightlife centre" , "Colourful district in London's West End" , "London area; hunt call" , "Call a large market for software" .)