Tantrum, just a bit of petulance (3)
I believe the answer is:
pet
'tantrum' is the definition.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for pet that I've seen before include "Caress - budgie, perhaps?" , "Particular favourite" , "Favourite, may be teacher's" , "A dear one exhibits sulkiness" , "Caress or fondle, as with favourite" .)