Tomb, laden, contains weapon (5)
I believe the answer is:
blade
'weapon' is the definition.
(blade is a kind of weapon)
'tomb laden contains' is the wordplay.
'contains' indicates the answer is hidden within the clue.
'BLADE' is hidden in the letters of 'tomb laden'.
(Other definitions for blade that I've seen before include "London rail terminus" , "Cutting part of grass?" , "cutter" , "Runner on an ice-skate" , "Flat part of an oar" .)