Bird in quantity of film after holiday cut short (6)
I believe the answer is:
toucan
'bird' is the definition.
(toucan is a kind of bird)
'quantity of film after holiday cut short' is the wordplay.
I cannot quite see how this works, but
'quantity' could be 'can' (can is a kind of quantity) and 'can' is located in the answer.
'of' could be 'o' and 'o' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for toucan that I've seen before include "Bird with large, colourful bill" , "Tropical American bird with immense beak" , "A pair could be able for this bird, by the sound of it" , "exotic bird" , "Tropical bird with large bill" .)