Sharply inclined to be exorbitant (5)
I believe the answer is:
steep
I believe this is a double definition.
'sharply inclined' is the first definition.
(I've seen this in another clue)
'be exorbitant' is the second definition.
(synonyms)
'to' is the link.
(Other definitions for steep that I've seen before include "over the top" , "Rapidly rising" , "not reasonable" , "Vertiginous; excessive" , "Marinate" .)