Division is Guardian's responsibility (4)

I believe the answer is:

ward

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'division' is the definition.
(I have seen 'Division of borough ' mean 'ward' so perhaps 'division' could also mean 'ward')

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for ward that I've seen before include "Division of borough" , "Doctor in 5A 1D [PROFUMO AFFAIR]" , "treatment room" , "number of patients" , "Minor with guardian - division of city" .)

I've seen this clue in The Independent.

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