Increase in anxiety no longer felt? (9)
I believe the answer is:
extension
I believe this clue is a double definition.
'increase' is the first definition.
(I know that extension is a type of enlargement)
'anxiety no longer felt?' is the second definition.
(I've seen this in another clue)
'in' is the link.
(Other definitions for extension that I've seen before include "Added part" , "Office phone, perhaps" , "Additional time for repayment" , "new wing" , "more rooms in house maybe" .)