Entering wood, everyone's about to fall down (8)
I believe the answer is:
collapse
'fall down' is the definition.
(thesaurus)
'entering wood everyone's about' is the wordplay.
'entering' is an insertion indicator.
'wood' becomes 'copse' (I've seen this before).
'everyone' becomes 'all' (I've seen this before).
'about' is a reversal indicator.
'all' reversed gives 'lla'.
'copse' enclosing 'lla' is 'COLLAPSE'.
'to' acts as a link.
(Other definitions for collapse that I've seen before include "Faint and fall" , "Crumble" , "Suddenly fall down or give way" , "Fall or disintergrate" , "Fall down as from weakness" .)