Fooling about in cavalry drama (9)

I believe the answer is:

horseplay

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'fooling about' is the definition.
'horseplay' can be an answer for 'fooling' (thesaurus). I am unsure of the 'about' bit.

'cavalry drama' is the wordplay.
'cavalry' becomes 'horse' (synonyms).
'drama' becomes 'play' (synonyms).
'horse'+'play'='HORSEPLAY'

'in' is the link.

Can you help me to learn more?

(Other definitions for horseplay that I've seen before include "rough and tumble" , "High jinks" , "clowning around" , "Rough boisterous action" , "In rough sport" .)

I've seen this clue in the Sydney Morning Herald.

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