Stir, mixing into after blending, and it’s very good (5-4)
I believe the answer is:
first-rate
'very good' is the definition.
'stir mixing into after blending and it's' is the wordplay.
'mixing' indicates an anagram.
'into' is an insertion indicator.
'after blending' becomes 'frat' (I am not sure about this - if you are sure you should believe this answer much more).
'and' means one lot of letters go next to another.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'stir' with letters rearranged gives 'irst'.
'irst' going inside 'frat' is 'firstrat'.
'firstrat'+'e'='FIRST-RATE'
Can you help me to learn more?
(Other definitions for first-rate that I've seen before include "Start fire to be really excellent" , "Stir after to be really excellent" , "Prime" , "Top-class, excellent" , "Top-notch, excellent" .)