Regressed (8)
I believe the answer is:
relapsed
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">regressed</span>' is the definition.<br/ ><span class="explanation-format__explanation">('relapse' can be a synonym of 'regress')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for relapsed that I've seen before include "Weakened" , "Regressed, got worse" , "Suffered setback" , "having become ill again" , "Returned to a poorer state of health" .)