Order around - the nerve! (5,4)
I believe the answer is:
about face
'order' is the definition.
(I've seen this before)
'around the nerve' is the wordplay.
'around' becomes 'about' (synonyms).
'the nerve' becomes 'face' ('face' can be a synonym of 'nerve').
'about'+'face'='ABOUT-FACE'
(Other definitions for about face that I've seen before include "U-turn" , "Military order to reverse position (5,4)" , "turnaround" , "Complete change of direction" , "order at West Point" .)