Baby girl entering is an angel (6)
I believe the answer is:
cherub
This might be a double definition.
'baby girl entering' is the first definition.
'cherub' can be an answer for 'baby' (I have seen 'Innocent baby ' mean 'cherub' so perhaps 'baby' could also mean 'cherub'). I am unsure of the 'girl entering' bit.
'an angel' is the second definition.
(cherub is a kind of angel)
'is' acts as a link.
Can you help me to learn more?
(Other definitions for cherub that I've seen before include "Sweet, innocent child" , "Angel portrayed as a winged child" , "overweight child" , "Sweet little baby" , "Angelic baby" .)