She's in a state of ruin, but will serve to introduce (5,2)
I believe the answer is:
usher in
'introduce' is the definition.
(I know that introduce can be written as usher in)
'she's in a state of ruin but will serve' is the wordplay.
I cannot really see how this works, but
'in' is within the answer.
'state' could be 'us' (US is an example) and 'us' is present in the answer.
'she' could be 'her' (I've seen this in other clues) and 'her' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Another definition for usher in that I've seen is " Introduce".)