Form taken by film when you spool up? (5)

I believe the answer is:

loops

I'm a little stuck... Click here to teach me more about this clue!

'form taken by film when you' is the definition.
I can't tell whether this definition defines the answer.

'spool up?' is the wordplay.
'up?' is a reversal indicator (in down clue: letters go upwards).
'spool' written backwards gives 'LOOPS'.

Can you help me to learn more?

(Other definitions for loops that I've seen before include "Oval-shaped single coils, in a piece of thread perhaps" , "Twists" , "Winds" .)

I've seen this clue in the Evening Standard.

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