Branch cancelled filming session (8)
I believe the answer is:
offshoot
'branch' is the definition.
(I know that branch can be written as offshoot)
'cancelled filming session' is the wordplay.
'cancelled' becomes 'off' (similar in meaning).
'filming session' becomes 'shoot' (I've seen this in another clue).
'off'+'shoot'='OFFSHOOT'
(Other definitions for offshoot that I've seen before include "Development" , "Derivative; scion" , "Something developing from another" , "Outgrowth or by-product" , "Side growth" .)