Changing the finale of a concert can cause worry (7)
I believe the answer is:
concern
'worry' is the definition.
(synonyms)
'changing the finale of a concert can cause' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is found in the answer.
'cause' could be 'rn' (RN is an example) and 'rn' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for concern that I've seen before include "Firm - interest" , "Affect; solicitude" , "Business - anxiety" , "Cause of anxiety" , "Feeling of anxiety or sympathy" .)