Lead first of children into English class (6)
I believe the answer is:
'lead' is the definition.
(I've seen this before)
'first of children into english class' is the wordplay.
'first of' says to take the initial letters.
'into' is an insertion indicator.
'english' becomes 'e' (abbreviation).
'class' becomes 'sort' ('sort' can be a synonym of 'class').
The first letter of 'children' is 'c'.
'c' inserted inside 'esort' is 'ESCORT'.
(Other definitions for escort that I've seen before include "guide", "Custodian", "going in convoy", "Ford car, first produced in 1968", "17 [DESTROYER]".)