Careful management of refurbished cast-iron oven (12)
I believe the answer is:
conservation
'careful management' is the definition.
(eg management of a resource)
'refurbished cast-iron oven' is the wordplay.
'refurbished' indicates an anagram.
'cast'+'iron'+'oven'='castironoven'
'castironoven' is an anagram of 'CONSERVATION'.
'of' acts as a link.
(Other definitions for conservation that I've seen before include "Preservation (of wildlife)" , "Care and maintenance of the environment" , "good husbandry" , "Careful use (of a resource)" , "management of natural resources" .)