Show undue pride, having left the butter out? (5)
I believe the answer is:
gloat
'show undue pride' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'left the butter out?' is the wordplay.
'left' becomes 'L' (common abbreviation).
'the butter' becomes 'goat' (animal which butts).
'out?' indicates putting letters inside.
'l' going inside 'goat' is 'GLOAT'.
'having' is the link.
Can you help me to learn more?
(Other definitions for gloat that I've seen before include "Exult over one's good fortune" , "Look triumphant" , "Exult maliciously" , "Look like the cat who got the cream" , "Be full of malicious delight" .)