Lecturer's first point of minimal importance (5)
I believe the answer is:
least
'of minimal importance' is the definition.
(I've seen this in another clue)
'lecturer's first point' is the wordplay.
'lecturer's first' becomes 'l' (1st letter of 'lecturer').
'point' becomes 'east' (east is a kind of point).
'l'+'east'='LEAST'
(Other definitions for least that I've seen before include "Smallest in extent" , "Lowest amount" , "Of minimal significance" , "Lowest or smallest" , "Most insignificant" .)