Suckling site (4)
I believe the answer is:
teat
'suckling site' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for teat that I've seen before include "Piece on baby's bottle" , "essential for babies" , "Nipple or dug" , "Part of feeding bottle" , "Bulb on infant's bottle" .)