Peter, Christ’s first volunteer (6)
I believe the answer is:
coffer
'peter' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'christ's first volunteer' is the wordplay.
'christ's first' becomes 'c' (1st letter of 'christ').
'volunteer' becomes 'offer' (synonyms).
'c'+'offer'='COFFER'
Can you help me to learn more?
(Other definitions for coffer that I've seen before include "Small chest for keeping valuables" , "A large strong box for valuables" , "Strong box at the treasury" , "Strongbox" , "Money chest sounds like one with lung trouble" .)