School's shooting film in the 1990s (13)

I believe the answer is:

trainspotting

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'the 1990s' is the definition.
I can't tell whether this definition defines the answer.

'school's shooting film' is the wordplay.
'school' becomes 'train' (training is a kind of schooling).
'shooting film' becomes 'spotting' (I can't explain this - if you can you should believe this answer much more).
'train'+'spotting'='TRAINSPOTTING'

'in' is the link.

Can you help me to learn more?

(Other definitions for trainspotting that I've seen before include "Film about drug addicts (or railway buffs?)" , "hobby" , "1996 film based on a novel by Irvine Welsh" .)

I've seen this clue in The Times.

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