Flightless bird in Prague museum (3)
I believe the answer is:
emu
'flightless bird' is the definition.
(emu is a kind of flightless bird)
'in prague museum' is the wordplay.
'in' indicates a hidden word.
'EMU' is hidden in the letters of 'prague museum'.
(Other definitions for emu that I've seen before include "Flightless Aus. bird" , "European project" , "Parky's nemesis" , "Large Australian flightless bird" , "it can't get off the ground" .)