Tory heading European research centre? It’s a worry (7)
I believe the answer is:
Here is my best explanation:
'a worry' is the definition.
('concern' can be a synonym of 'worry')
'tory heading european research centre?' is the wordplay.
'tory' becomes 'con' (I've seen this before).
'heading' is a charade indicator (letters next to each other) (some letters go in front of or head others).
'european research centre?' becomes 'cern' (scientific research centre CERN).
'it's' is the link.
(Other definitions for concern that I've seen before include "Disquiet", "Cause of anxiety", "Interest", "Feeling of anxiety or sympathy", "Anxiety; business", "Affair", "Firm - interest", "Business - anxiety", "Involve" and "Affect; solicitude".)