Soldiers coming to wood, a testing experience (6)
I believe the answer is:
ordeal
'a testing experience' is the definition.
(I've seen this before)
'soldiers coming to wood' is the wordplay.
'soldiers' becomes 'or' (Other Rank).
'coming to' is a charade indicator (letters next to each other).
'wood' becomes 'deal' (deal is a kind of wood**).
'or'+'deal'='ORDEAL'
(Other definitions for ordeal that I've seen before include "Difficult and testing experience" , "Struggle" , "A tough and testing time" , "Prolonged suffering, difficult to endure" , "A tough time or hardship" .)