Show soldiers meat from farm animal (6)
I believe the answer is:
reveal
'show' is the definition.
(I know that reveal is a type of show)
'soldiers meat from farm animal' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'meat from farm animal' becomes 'veal' (meat of a calf).
're'+'veal'='REVEAL'
(Other definitions for reveal that I've seen before include "Expose or display" , "window, in part" , "Final disclosure" , "'Make known, disclose (6)'" , "Spill beans" .)