New member annoyed courtier dropping ball (7)
I believe the answer is:
recruit
'new member' is the definition.
(I've seen this before)
'annoyed courtier dropping ball' is the wordplay.
'annoyed' indicates an anagram.
'dropping' is a deletion indicator.
'ball' becomes 'o'.
'courtier' with 'o' removed is 'curtier'.
'curtier' anagrammed gives 'RECRUIT'.
(Other definitions for recruit that I've seen before include "Trainee" , "Recently enlisted person" , "Enlist (someone) into the armed forces" , "Novice" , "Take on" .)