Half-sister of Absalom (5)
I believe the answer is:
tamar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">half-sister of absalom</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 tamar that I've seen before include "West Country river; a tram (anag.)" , "River in south-west" , "River of SW_England" , "Devon-Cornwall boundary river" , "Plymouth river" .)