Part of administration's relative magnitude (5)

I believe the answer is:

ratio

'relative magnitude' is the definition.
(I've seen this before)

'part of administration's' is the wordplay.
'part of' indicates a hidden word.
'RATIO' is hidden within 'administrations'.

(Other definitions for ratio that I've seen before include "Mathematical relationship" , "nine-to-five, say" , "Proportional relation between two numbers" , "Relativity between two quantities" , "allowance" .)

I've seen this clue in The Telegraph.

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