Monroe's successor (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">monroe's successor</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for adams that I've seen before include "Of untidy appearance" , "Father and son were American presidents" , "Name of two early US presidents" , "Richard --, Watership Down author" , "Presidential father or son" .)