Commute in coaches lacking one class (9)
I believe the answer is:
transform
'commute' is the definition.
(I've seen this in another clue)
'coaches lacking one class' is the wordplay.
'coaches' becomes 'trains' (coach can mean to train or educate).
'lacking' suggests deleting specific letters.
'one' becomes 'i' (Roman numeral).
'class' becomes 'form' (form class is a kind of class).
'trains' with 'i' taken out is 'trans'.
'trans'+'form'='TRANSFORM'
'in' acts as a link.
(Other definitions for transform that I've seen before include "Subject to change" , "adapt" , "Change completely" , "Remodel" , "Change the voltage I" .)