Anger about navy is concerning (2,2)
I believe the answer is:
in re
'is concerning' is the definition.
(short for 'in regards to' ie concerning a topic)
'anger about navy' is the wordplay.
'anger' becomes 'ire' (ire is intense rage).
'about' indicates putting letters inside.
'navy' becomes 'N' (common abbreviation eg in RN Royal Navy).
'ire' placed around 'n' is 'IN RE'.
(Other definitions for in re that I've seen before include "In the matter of (Lat.)" , "Concerning (L)" , "With regard to" .)