Ransacked train regularly then ran away (6)
I believe the answer is:
rifled
'ransacked' is the definition.
('rifle' can be a synonym of 'ransack')
'train regularly then ran away' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'then' says to put letters next to each other.
'ran away' becomes 'fled' (I've seen this in another clue).
The alternating letters of 'train' are 'ri'.
'ri'+'fled'='RIFLED'
(Other definitions for rifled that I've seen before include "Searched through" , "Ransacked" .)