Not all panellists can show much panache! (4)
I believe the answer is:
elan
'panache' is the definition.
(I know that panache can be written as elan)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for elan that I've seen before include "Impressive and energetic style" , "Flair and dash" , "French verve" , "French vivacity" , "Vitality" .)