Intellectual English master inspiring good grades at first (7)
I believe the answer is:
egghead
'intellectual' is the definition.
(I know that egghead is a type of intellectual)
'english master inspiring good grades at first' is the wordplay.
'english' becomes 'E' (abbreviation).
'master' becomes 'head' (I am not sure about this - if you are sure you should believe this answer much more).
'inspiring' is an insertion indicator.
'at first' indicates taking the first letters.
The initial letters of 'good grades' is 'gg'.
'e'+'head'='ehead'
'ehead' placed around 'gg' is 'EGGHEAD'.
Can you help me to learn more?
(Other definitions for egghead that I've seen before include "Heed gag about slang intellectual" , "Intellectual, studious academic" , "Expert" , "Informal intellectual of ovoid type" , "Very academic person" .)