Modern English:
1.) (of food) full of juice; succulent. (i.e. "a juicy apple")
synonyms: succulent, tender, moist; More ripe;
antonyms: dry
2.) interestingly scandalous. (i.e. "juicy gossip")
synonyms: sensational, very interesting, fascinating, lurid; More scandalous, racy, risqué, spicy;
antonyms: dull
3.) temptingly appealing. (i.e. "the promise of juicy returns on an investment")
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All three could apply to beer but interestingly enough the 1st definition which applies to food may only apply to the notion that fruity smelling hops give beer a "fruit juice" aroma (an aroma full of the smell of fruit juice).
Of course you could, but I don't think one would normally say the same about "grassy", "earthy" or "spicy" smelling hops (i.e. noble hops). The second definition does open up this possibility.
Therefore a beer described as "juicy" better have some fruity smelling hops/esters otherwise the meaning is totally obscure and inappropriate (unless of course it refers to an appealing beer, which would also be a rather obscure use).