wood ply separation

[gaj@popmail3.vnet.net]

I have a client who has a Kimball grand/high gloss finish whose plys of wood
that make up top cover of piano has separated approx. 12 " in each direction
from one corner.  (This is the part of the piano that covers music desk,
tuning pins, etc.)  'Any suggestions as to kind of glue, clamping, etc. for
repair?

Thanks ahead!!  Ashley Johnson, So.Carolina