Bring up and care for (4)
'bring up and care for' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rear that I've seen before include "what you may bring up" , "Breed or bring up" , "Hitchcock film set in one room" , "Bring up - the tail" , "early, long before now" .)
(Other definitions for nurture that I've seen before include "Train" , "Nourishment" , "Run true (anag)" , "Rear (a child); cherish" , "Supply sustenance to" .)