Grizzly members go into battle (4,4)
I believe the answer is:
bear arms
'go into battle' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'grizzly members' is the wordplay.
'grizzly' becomes 'bear' (I've seen this before).
'members' becomes 'arms' (arm is a kind of member).
'bear'+'arms'='BEAR ARMS'
Can you help me to learn more?
(Other definitions for bear arms that I've seen before include "they may be used in a tight squeeze!" , "right for American?" , "Serve as a soldier" , "Carry weapons" , "Serve in the forces" .)