Universal life force (3)
I believe the answer is:
chi
'universal life force' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for chi that I've seen before include "Twenty-second Greek letter" , "character in Thessaloniki" , "The 22nd letter of Greek alphabet" , "Letter written by European" , "T'ai -, martial art" .)