Express train leaves Berlin regularly (9)
I believe the answer is:
verbalise
'express' is the definition.
('express'->'verbalize' is in my internal thesaurus and 'ize'->'ise')
'train leaves berlin regularly' is the wordplay.
'train' indicates anagramming the letters (to train can mean to grow something into a shape).
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'berlin' are 'bri'.
'leaves'+'bri'='leavesbri'
'leavesbri' with letters rearranged gives 'VERBALISE'.
(Another definition for verbalise that I've seen is " Put into words".)