Dash around during vernal equinox
I believe the answer is:
elan
'dash' is the definition.
('elan' can be a synonym of 'dash')
'around during vernal equinox' is the wordplay.
'around' shows that the letters should be reversed in order.
'during' says the answer is hidden in the clue.
'nale' is hidden in the letters of 'vernal equinox'.
'nale' backwards is 'ELAN'.
(Other definitions for elan that I've seen before include "Style and verve" , "Stylish enthusiasm" , "Snap" , "Vivacity, dash" , "Vigour, panache" .)