Relevant article on surgery accepted by experts (7)
I believe the answer is:
apropos
'relevant' is the definition.
(I've seen this before)
'article on surgery accepted by experts' is the wordplay.
'article' becomes 'a' (the indefinite article in English).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'surgery' becomes 'op' (short for operation).
'accepted by' is an insertion indicator (inserted letters are accepted).
'experts' becomes 'pros' (professionals).
'op' put within 'pros' is 'propos'.
'a'+'propos'='APROPOS'
(Other definitions for apropos that I've seen before include "With reference to, concerning" , "In respect of" , "Suitable or relevant" , "As regards" , "To the point about poor spa" .)