Every single one of the peaches (4)
I believe the answer is:
each
'every single' is the definition.
(I've seen this before)
'one of the peaches' is the wordplay.
'one of' indicates a hidden word.
'EACH' can be found hidden inside 'peaches'.
(Other definitions for each that I've seen before include "every one individually" , "Every single one, person or thing" , "Singly, per capita" , "Ache (anag.)" , "This way for a place" .)