Initially missed out, angry newbies complain (4)
I believe the answer is:
moan
'complain' is the definition.
(moan can mean to complain or whinge)
'initially missed out angry newbies' is the wordplay.
'initially' indicates taking the first letters.
The first letters of 'missed out angry newbies' is 'MOAN'.
(Other definitions for moan that I've seen before include "Complain; rhymes with money lent" , "Lament; grumble" , "Complain, groan" , "Complain; mournful sound" , "Keen" .)