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I'm sorry but I've tried every search combination I can think of to find your Eevee but cannot find any Eevee looking for a Clefairy in exchange.
The only options that I can think of to get this through GTS are that I deposit Clefairy for your Eevee or else you use another mon with a higher level. I've got to go out now for a couple of hours so I'll check back later.
Nickname VooDoo96