Gem that's very bad being put back in container (7)
I believe the answer is:
peridot
'gem' is the definition.
(peridot is a kind of gem)
'very bad being put back in container' is the wordplay.
'very bad' becomes 'dire'.
'being put back' says the letters should be written backwards.
'in' indicates putting letters inside.
'container' becomes 'pot' (pot is a kind of container).
'dire' reversed gives 'erid'.
'erid' going into 'pot' is 'PERIDOT'.
'that's' acts as a link.
(Other definitions for peridot that I've seen before include "Gem" , "Pale green gemstone" , "I deport (anag) - gemstone" , "Top ride (anag) - gemstone" , "Gemstone -- pre-do it (anag)" .)