They feed the young and you, we hear, over summers, not initially (6)
I believe the answer is:
udders
'they feed the young' is the definition.
(eg a cow's udders feed her young)
'you we hear over summers not initially' is the wordplay.
'we hear' indicates a 'sounds like' (homophone) clue.
'over' means one lot of letters go next to another.
'summers' becomes 'adders' (people who add or sum up).
'not initially' means to remove the first letter.
'you' sounds like 'u'.
'adders' with its initial letter taken off is 'dders'.
'u'+'dders'='UDDERS'
'and' is the link.
(Other definitions for udders that I've seen before include "These full of milk" , "de rest" , "Cows' teats" , "Mammary glands of cows" , "Bovine mammary glands" .)