Object vaporised after mixing around phosphorus (10)
I believe the answer is:
disapprove
'object' is the definition.
(to object to something is to disapprove of it)
'vaporised after mixing around phosphorus' is the wordplay.
'after mixing' is an anagram indicator.
'around' is an insertion indicator.
'phosphorus' becomes 'P' (P is the chemical symbol for phosphorus).
'vaporised' is an anagram of 'disaprove'.
'disaprove' enclosing 'p' is 'DISAPPROVE'.
(Other definitions for disapprove that I've seen before include "Censure" , "Not like" , "mind" , "Reject" , "Not be happy with" .)