Recent arrivals sadly eat in kitchen at first (6)
I believe the answer is:
intake
'recent arrivals' is the definition.
(eg the new intake at a school)
'sadly eat in kitchen at first' is the wordplay.
'sadly' indicates an anagram.
'at first' says to take the initial letters.
The first letter of 'kitchen' is 'k'.
'eat'+'in'+'k'='eatink'
'eatink' with letters rearranged gives 'INTAKE'.
(Other definitions for intake that I've seen before include "new kids?" , "Group of new students" , "Number of people or things accepted or received" , "Place where gas or water enters" , "Body of new pupils" .)