Session (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">session</span>' is the definition.<br/ ><span class="explanation-format__explanation">(sitting is a kind of session)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sitting that I've seen before include "Session of spiritualists or court" , "such an easy target" , "Well placed" , "Being portrayed" , "On a seat" .)
(Other definitions for jam that I've seen before include "Preserve - predicament" , "Spread; improvise (jazz)" , "Preserve; pack tightly" , "Fruit preserve" , "Block signals" .)