'Art house' trailing great old film (7)
I believe the answer is:
acetate
'old film' is the definition.
'acetate' can be an answer for 'film' (I've seen this before). I am unsure of the 'old' bit.
'art house trailing great' is the wordplay.
'art house' becomes 'tate' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'trailing' says to put letters next to each other.
'great' becomes 'ace' (ace can informally mean very good).
'tate' after 'ace' is 'ACETATE'.
Can you help me to learn more?
(Other definitions for acetate that I've seen before include "(Chemical used in production of) clear film" , "Material in old record" , "Artificial textile fibre" , "Synthetic fabric" , "It once covered records" .)