Queen's travelling by this French train (8)
I believe the answer is:
'train' is the definition.
'queen's travelling by this french' is the wordplay.
'travelling' indicates an anagram.
'by' says to put letters next to each other.
'this french' becomes 'ce' (I've seen this in other clues).
'queens' is an anagram of 'sequen'.
(Other definitions for sequence that I've seen before include "Arrangement of things in order" , "Serial arrangement following a logical order or recurrent pattern" , "26 [ORDER]" , "Arrangement in a certain order" , "Where things follow in logical order or recurrent pattern" .)