Endlessly stylish Greek character (3)
I believe the answer is:
chi
'greek character' is the definition.
(letter from the Greek alphabet)
'endlessly stylish' is the wordplay.
'endlessly' means to remove the last letter.
'stylish' becomes 'chic' ('chic' can be similar in meaning to 'stylish').
'chic' with its final letter taken off is 'CHI'.
(Other definitions for chi that I've seen before include "In Chinese medicine, the life force inherent in all things" , "seen in Greek writing" , "character from Euripides?" , "The life force, according to traditional Chinese medicine" , "Twenty-second Greek letter" .)