Notices new military group (7)
I believe the answer is:
section
'military group' is the definition.
(I know that section is a type of army unit)
'notices new' is the wordplay.
'new' indicates an anagram.
'notices' anagrammed gives 'SECTION'.
(Other definitions for section that I've seen before include "unit" , "surgical procedure" , "Cut" , "Segment" , "Divide; part" .)