Related Clues:

• Fuse into one
• Become as one
• Make two companies one
• Marxist exhortation to 'workers of the world'
• Bond in sight of gun — it explodes
• Mingle with grockles, initially, in pool
• Command in Excel
• Wed, say
• Posh evening reported for couple
• Sign at the end of a ramp
• Join fool in backing European Union
• Join (the reverse of it here would suggest 'loosen')
• Get involved in someone else's business?
• Rallier's cry
• EU retaining money raised for ally