We study the clustering Generalized Chaplygin Gas ( GCG ) as a possible candidate for dark matter-dark energy unification .
The vanishing speed of sound ( c _ { s } ^ { 2 } = 0 ) for the GCG fluid can be obtained by incorporating higher derivative operator in the original K-essence Lagrangian .
The evolution of the density fluctuations in the GCG+Baryon fluid is studied in the linear regime .
The observational constraints on the model are obtained using latest data from SNIa , H ( z ) , BAO and also for the f \sigma _ { 8 } measurements .
The matter power spectra for the allowed parameter values are well behaved without any unphysical features .