Worry about taking expert on in meeting (9)
I believe the answer is:
interface
'meeting' is the definition.
(point where two things meet)
'worry about taking expert on in' is the wordplay.
I cannot quite see how this works, but
'about' could be 'c' (circa abbreviation) and 'c' is located in the answer.
'in' is present in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for interface that I've seen before include "Meeting point" , "meeting-point" , "Boundary" , "Windows, for example" , "Point where two thing meet" .)