Nanny rating Times covers (4)
I believe the answer is:
baby
'nanny' is the definition.
(both can mean to treat someone like a child)
'rating times covers' is the wordplay.
'rating' becomes 'ab'.
'times' becomes 'by' (I've seen this in other clues).
'covers' is an insertion indicator.
'ab' placed within 'by' is 'BABY'.
(Other definitions for baby that I've seen before include "Bunting" , "Very young person" , "One born" , "needing dummy?" , "Infant" .)