Move away from contrary babies, every so often (3)
I believe the answer is:
ebb
'move away' is the definition.
(ebbing is a kind of moving away)
'contrary babies every so often' is the wordplay.
'contrary' says the letters should be written in reverse.
'every so often' means one should take alternating letters.
The alternate letters of 'babies' are 'bbe'.
'bbe' in reverse letter order is 'EBB'.
'from' is the link.
(Other definitions for ebb that I've seen before include "Type of tide" , "Fall back" , "(Of tidewater) recede" , "Receding movement, as of a tide" , "Initially Mrs Browning's" .)