Regular classes taken by inexperienced driver (7)
I believe the answer is:
general
'regular' is the definition.
(I've seen this before)
'classes taken by inexperienced driver' is the wordplay.
'classes' becomes 'genera' (more than one genus - a class or category).
'taken by' means one lot of letters go next to another.
'inexperienced driver' becomes 'l' (a learner driver's car carries L-plates).
'genera'+'l'='GENERAL'
(Other definitions for general that I've seen before include "Rank; all-inclusive" , "Popular" , "Not particular or specific" , "top brass" , "High ranking officer" .)