In very good health (3,2,1,6)
I believe the answer is:
fit as a fiddle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">in very good health</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for fit as a fiddle that I've seen before include "In the pink" , "Extremely healthy" , "In very good health" , "Flourishing" , "Bouncing with health" .)