Wife has rings to widen skirt, that is for baby's movement (8)

'skirt that is for baby's movement' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'wife has rings to widen' is the wordplay.
'wife has' becomes 'wie' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rings' becomes 'hoops' ('hoop' can be a synonym of 'ring').
'to widen' is an insertion indicator (inserted letters make the original word wider).
'wie' enclosing 'hoops' is 'WHOOPSIE'.

Can you help me to learn more?