Being a goody-goody, is less than sprightly (4)
I believe the answer is:
prig
'being a goody-goody is' is the definition.
I can't tell whether this defines the answer.
'less than sprightly' is the wordplay.
'less' indicates a hidden word (the clue less some of the letters in it).
'PRIG' is hidden within 'than sprightly'.
Can you help me to learn more?
(Other definitions for prig that I've seen before include "Snob" , "Sanctimonious person" , "Puritan" , "Self-righteous moralist" , "Smugly self-righteous person" .)