Soldiers left in charge of a venerated object (5)
I believe the answer is:
relic
'a venerated object' is the definition.
(I've seen this in another clue)
'soldiers left in charge' is the wordplay.
'soldiers' becomes 're' (Royal Engineers regiment).
'left' becomes 'l' (common abbreviation).
'in charge' becomes 'ic' (abbreviation for 'in charge').
're'+'l'+'ic'='RELIC'
'of' is the link.
(Other definitions for relic that I've seen before include "Long-surviving object" , "Reminder of times past" , "A survival from the past" , "Item surviving from the past" , "Survival from an earlier time" .)