Nursemaids who may be grandmothers (7)

I believe the answer is:

nannies

I'm a little stuck... Click here to teach me more about this clue!

'nursemaids' is the definition.
(I know this)

I cannot understand how the remainder of the clue works.

(Other definitions for nannies that I've seen before include "She-goats" , "Female goats" , "nursemaids" , "Children's nurses" , "Child minders" .)

I've seen this clue in the Evening Standard.

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