Current doctor to protect by putting on thick coat (7)
I believe the answer is:
impasto
'thick coat' is the definition.
(I've seen this before)
'current doctor to protect by putting' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'doctor' becomes 'mo' (medical officer).
'to protect' indicates putting letters inside.
'by putting' becomes 'past' (I can't explain this - if you can you should believe this answer much more).
'mo' going around 'past' is 'mpasto'.
'i'+'mpasto'='IMPASTO'
'on' is the link.
Can you help me to learn more?
(Other definitions for impasto that I've seen before include "Thick coat required" , "Thick painting technique" , "artist's application" , "Slapping paint on" , "Method of painting" .)