Public disturbances contained without one item of police equipment (4,6)
I believe the answer is:
riot shield
'item of police equipment' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'public disturbances contained without one' is the wordplay.
'public disturbances' becomes 'riots' (I've seen this in another clue).
'contained' becomes 'held' ('hold' can be a synonym of 'contain').
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'one' becomes 'i' (Roman numeral).
'held' going around 'i' is 'hield'.
'riots'+'hield'='RIOT SHIELD'
Can you help me to learn more?
(Another definition for riot shield that I've seen is " guard employed by police".)