The Collaborative International Dictionary of English v.0.48:

Shandygaff \Shan"dy*gaff\, n.
   A mixture of strong beer and ginger beer. [Eng.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

shandygaff
    n 1: a drink made of beer and lemonade [syn: shandygaff,
         shandy]