Letter before psi (3)
I believe the answer is:
chi
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">letter before psi</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 chi that I've seen before include "foreign character" , "Greek letter; Chinese life force" , "One character abroad" , "Twenty-second Greek letter" , "The life force, according to traditional Chinese medicine" .)