Expert in deformation of silicates doped with phosphorus (10)
I believe the answer is:
specialist
'expert' is the definition.
(specialist is a kind of expert)
'deformation of silicates doped with phosphorus' is the wordplay.
'deformation of' indicates anagramming the letters (the original order of letters should be deformed).
'doped with' is an insertion indicator (to inject an animal with something is to dope it).
'phosphorus' becomes 'p' (P is the chemical symbol for phosphorus).
'silicates' is an anagram of 'secialist'.
'secialist' going around 'p' is 'SPECIALIST'.
'in' acts as a link.
(Other definitions for specialist that I've seen before include "Expert" , "particular skill" , "One skilled in a specific field" , "One skilled in a limited field" .)