As leader of government had written about English intellectual (7)
I believe the answer is:
egghead
'intellectual' is the definition.
(egghead is a kind of intellectual)
'as leader of government had written about english' is the wordplay.
'as' becomes 'eg' (I've seen this in other clues).
'leader of' says to take the initial letters.
'written about' indicates putting letters inside.
'english' becomes 'e' (abbreviation).
The first letter of 'government' is 'g'.
'had' placed around 'e' is 'head'.
'eg'+'g'+'head'='EGGHEAD'
(Other definitions for egghead that I've seen before include "Intellectual - highbrow" , "Intellectual, studious academic" , "Very clever person" , "Brainbox" , "Intellectual (colloq.)" .)