The birds and the bees leaving babes five slices (4)
I believe the answer is:
aves
'the birds' is the definition.
(I've seen this in another clue)
'the bees leaving babes five slices' is the wordplay.
'the bees' becomes 'bb' (the letter B written twice).
'leaving' is a deletion indicator.
'five' becomes 'V' (Roman numeral).
'slices' is an insertion indicator (some letters slice into others).
'babes' with 'bb' removed is 'aes'.
'aes' placed around 'v' is 'AVES'.
'and' is the link.
(Another definition for aves that I've seen is " Reverential salutations: class of vertebrates which comprises birds".)