Forgive former open container use (6)
I believe the answer is:
excuse
'forgive' is the definition.
(I know that excuse is a more specific form of absolve)
'former open container use' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'open' suggests taking the first letters (take the opening letter).
The initial letter of 'container' is 'c'.
'ex'+'c'+'use'='EXCUSE'
(Other definitions for excuse that I've seen before include "A defence for bad behaviour" , "Forgive or overlook an offence" , "Absolve" , "Free - apology" , "Mitigate; forgive" .)