With a gift the members make a uniform greeting (7,4)
I believe the answer is:
present arms
'a uniform greeting' is the definition.
The definition suggests a singular noun which matches the answer.
'with a gift the members' is the wordplay.
'with' says to put letters next to each other.
'a gift' becomes 'present' (present is a kind of gift).
'the members' becomes 'arms' (arm is a kind of member).
'present' put next to 'arms' is 'PRESENT ARMS'.
'make' is the link.
Can you help me to learn more?
(Other definitions for present arms that I've seen before include "offer to restore Venus de Milo?" , "Hold rifle vertically as a salute" , "Military drill command" , "Raise a weapon in salute" , "order needed" .)