Train due, ETA adjusted to accommodate first of cancellations (7)
I believe the answer is:
educate
'train' is the definition.
(I know that train can be written as educate)
'due eta adjusted to accommodate first of cancellations' is the wordplay.
'adjusted' indicates anagramming the letters.
'to accommodate' is an insertion indicator.
'first of cancellations' becomes 'c' (1st letter of 'cancellations').
'due'+'eta'='dueeta'
'dueeta' with letters rearranged gives 'eduate'.
'eduate' enclosing 'c' is 'EDUCATE'.
(Other definitions for educate that I've seen before include "Teach - instruct" , "teaching style" , "Tutor" , "Inform" , "Train, teach" .)