Absolute silence in tree (3)
I believe the answer is:
ash
'tree' is the definition.
(ash is a kind of tree)
'absolute silence' is the wordplay.
'absolute' becomes 'a' (this could be a standard abbreviation I've not previously seen).
'silence' becomes 'sh' ('sh' is said to tell someone to be silent).
'a'+'sh'='ASH'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for ash that I've seen before include "Grey-barked tree" , "What's often left after something 1 Ac" , "Part of forest" , "Rowan tree is also called the mountain . . ." , "Burnt material; tree" .)