Oil jars built with care (9)
I believe the answer is:
lubricate
'oil' is the definition.
(synonyms)
'jars built with care' is the wordplay.
'jars' indicates anagramming the letters (the letters must be shocked or jarred).
'with' means one lot of letters go next to another.
'built' after 'care' is 'carebuilt'.
'carebuilt' with letters rearranged gives 'LUBRICATE'.
(Other definitions for lubricate that I've seen before include "Apply oil/grease" , "supply with booze" , "Coat with oil to reduce friction" , "Oil (a mechanism)" , "Apply oil or grease to" .)