Crossword Genius

Offensives where films are shot (6)

Ross

I believe the answer is:

onsets

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

'offensives' is the definition.
The answer and definition can be both acts as well as being plural nouns.
Maybe there's a link between them I don't understand?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Another definition for onsets that I've seen is " Attacks with stones".)

I've seen this clue in The Hindu.
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