Quality surprisingly found among the languid (4)
I believe the answer is:
'quality' is the definition.
(elan is a kind of quality)
'among the languid' is the wordplay.
'among' says the answer is hidden in the clue.
'ELAN' is hidden within 'the languid'.
'surprisingly found' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for elan that I've seen before include "Energetic style - anagram of 3" , "Flamboyance" , "Verve and dash" , "Vigour, panache" , "Stylishness" .)