The train isn’t moving, or travelling (2,7)
I believe the answer is:
in transit
'travelling' is the definition.
'the train isn't moving' is the wordplay.
'moving' indicates an anagram.
'train'+'isnt'='trainisnt'
'trainisnt' is an anagram of 'IN TRANSIT'.
'or' acts as a link.
(Other definitions for in transit that I've seen before include "during journey" , "(Of goods) being moved" , "while travelling" , "on the move?" , "En route" .)