Christian virtue of work embraced by ambassador (4)
I believe the answer is:
hope
'christian virtue' is the definition.
(hope is a virtue)
'work embraced by ambassador' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'embraced by' indicates putting letters inside.
'ambassador' becomes 'he' (His or Her Excellency).
'op' put inside 'he' is 'HOPE'.
'of' acts as a link.
(Other definitions for hope that I've seen before include "Feeling of optimism" , "Companion to faith and charity" , "The Cape of Good -" , "Trustful expectation" , "confidence" .)