Does it follow the film advertised? (7)

I believe the answer is:
trailer
'film advertised?' is the definition.
I know that 'film' relates to this answer.
'does it follow' is the wordplay.
I cannot quite see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
The remaining letters 'railer' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'the' is the link.
Can you help me to learn more?
(Other definitions for trailer that I've seen before include "Extract for advance publicity" , "Rear section of an articulated lorry" , "Short scenes from a future film" , "Retrial (anag)" , "It follows a car but may be seen in the cinema" .)
