Subject to (5)
I believe the answer is:
under
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">subject to</span>' is the definition.<br/ ><span class="explanation-format__explanation">(being subject to a law is being under it)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for under that I've seen before include "Less than" , "See 16 Down" , "In the process of" , "Dylan Thomas radio play ''.... Milk Wood''" , "Governed by" .)