Related Clues:

• Close associate
• Great Britain, vis-a-vis the United States
• Combine against, with ''on''
• Friend in need, perhaps
• Ally (with)
• Sign up (for)
• Lose one's identity
• Pact participant
• Form an alliance
• Change from two to one
• Friend by treaty
• Prepare to serve
• One on your side
• Pact partner
• Unite, as 57-Across and Time Warner in 2000