He insists on minutiae and bursts into a tantrum (6)
I believe the answer is:
pedant
'he insists on minutiae' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'and bursts into a tantrum' is the wordplay.
'bursts' indicates an anagram.
'into' is an insertion indicator.
'a tantrum' becomes 'pet'.
'and' anagrammed gives 'dan'.
'dan' placed into 'pet' is 'PEDANT'.
Can you help me to learn more?
(Other definitions for pedant that I've seen before include "Person who pays too much attention to formal rules" , "quibbler" , "Academic stickler" , "One particular" , "Person who is strict on rules and details" .)