Legally prohibit (5)
I believe the answer is:
estop
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">legally prohibit</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for estop that I've seen before include "term in law" , "Legally check" , "Legal term" , "Bar, for a lawyer" , "Preclude certain evidence (at law) - bar (archaic)" .)