Cook in harem missed little in retirement (6)
I believe the answer is:
simmer
'cook' is the definition.
(I've seen this before)
'harem missed little in retirement' is the wordplay.
'in' says the answer is hidden in the clue.
'retirement' says the letters should be written in reverse (retire can mean to return or go back).
'remmis' can be found hidden inside 'harem missed little'.
'remmis' backwards is 'SIMMER'.
'in' is the link.
(Other definitions for simmer that I've seen before include "Cook just below boiling point" , "Keep just short of boiling point, water or temper" , "Boil slowly at low temperature" , "Bubble away" , "Seethe" .)