Possible Clues:

• That's the very one that's sprightly
• "We have nothing to fear but fear ---"
• The "se" in per se
• '... is fear ___': F.D.R.
• That's the very thing that's sprightly
• Reflexive word - stifle (anag)
• Intensifying word
• Reflexive form for something already mentioned
• Emphatic neuter pronoun
• That is sprightly - the very thing