Female chef, ultimately limited by time restriction, serves delicacy (7)
I believe the answer is:
truffle
'delicacy' is the definition.
(truffle is a kind of delicacy)
'female chef ultimately limited by time restriction' is the wordplay.
'female' becomes 'f' (abbreviation).
'ultimately' says to take the final letters.
'limited by' is an insertion indicator (limit can mean to contain or border off).
'time' becomes 't'.
'restriction' becomes 'rule'.
The final letter of 'chef' is 'f'.
'f'+'f'='ff'
't'+'rule'='trule'
'ff' inserted inside 'trule' is 'TRUFFLE'.
'serves' is the link.
(Other definitions for truffle that I've seen before include "Fungoid delicacy" , "Earthnut" , "Rich-flavoured fungus that grows undergrond" , "Fretful (anag)" , "Witty remark" .)