In returning communique, I'd nominate French, my Lord (3,4)
I believe the answer is:
mon dieu
'french my lord' is the definition.
('my lord' in French)
'in returning communique i'd nominate' is the wordplay.
'returning' says the letters should be written backwards.
'in' indicates the answer is hidden within the clue.
'ueidnom' is hidden within 'communique id nominate'.
'ueidnom' reversed gives 'MON DIEU'.
(Other definitions for mon dieu that I've seen before include "Stereotypical French exclamation" , "Quelle surprise" .)