Desert Orchid's kept light (5)
I believe the answer is:
torch
'light' is the definition.
(type of light)
'desert orchid's kept' is the wordplay.
'kept' indicates a hidden word.
'TORCH' can be found hidden inside 'desert orchids'.
(Other definitions for torch that I've seen before include "source of illumination" , "Set fire to - hand-held light" , "Set fire to; electric lamp" , "A large candle" , "Deliberately set fire to" .)