After first application, not to hold in or smear with oil (6)
I believe the answer is:
anoint
'smear with oil' is the definition.
(I've seen this before)
'after first application not to hold in' is the wordplay.
'after' means one lot of letters go next to another.
'first application' becomes 'a' (1st letter of 'application').
'to hold' is an insertion indicator.
'not' going around 'in' is 'noint'.
'a'+'noint' is 'ANOINT'.
'or' is the link.
(Other definitions for anoint that I've seen before include "Administer sacred oils as to the sick" , "Consecrate with blessed oils" , "Smear (with oil)" , "Put in position of authority" , "Consecrate with holy oil" .)