Advance care of yours truly (4)
I believe the answer is:
come
'advance' is the definition.
(I've seen this in other clues)
'care of yours truly' is the wordplay.
'care of' becomes 'co' (c/o can mean 'care of' when addressing mail).
'yours truly' becomes 'me' (the person that set this crossword).
'co'+'me'='COME'
(Other definitions for come that I've seen before include "See 13 across" , "Approach" , "Arrive" , "Draw near" , "' - - fly with me'" .)