What fiancee is tied up? (7)
I believe the answer is:
engaged
This clue is a double definition.
'what fiancee is' is the first definition.
(I know this)
'tied up?' is the second definition.
('engaged' can be a synonym of 'tied up')
(Other definitions for engaged that I've seen before include "Hired; busy" , "Held" , "Absorbed" , "Sweethearts may get it" , "Busy - fiancee" .)