Jungle, Amazonian, absorbing this flash of light (5)
I believe the answer is:
'this flash of light' is the definition.
(gleam means a sparkling light)
'jungle amazonian absorbing' is the wordplay.
'absorbing' indicates a hidden word.
'GLEAM' can be found hidden inside 'jungle amazonian'.
(Other definitions for gleam that I've seen before include "Beam of soft light, comes and goes" , "shaft" , "Brief bright light" , "Sparkle, glimmer" , "Brief shining" .)