More senior (5)
I believe the answer is:
older
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">more senior</span>' is the definition.<br/ ><span class="explanation-format__explanation">('old' is associated in meaning with 'senior')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for older that I've seen before include "Earlier" , "More elderly" , "Elder" , "Increasingly mature" , "Less young" .)