Jittery chaplaincy ousts cynic citing letter from Greece (5)
I believe the answer is:
alpha
'letter from greece' is the definition.
(letter from the Greek alphabet)
'jittery chaplaincy ousts cynic' is the wordplay.
'jittery' indicates an anagram.
'ousts' suggests deleting specific letters.
'chaplaincy' with 'cynic' removed is 'hapla'.
'hapla' is an anagram of 'ALPHA'.
'citing' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for alpha that I've seen before include "Top grade" , "high mark" , "European character" , "First in sequence" , "piece of Greek writing" .)