Itch in one's cab, ie scratchy (7)
I believe the answer is:
scabies
'itch' is the definition.
(I have seen 'The itch ' mean 'scabies' so perhaps 'itch' could also mean 'scabies')
'in one's cab ie scratchy' is the wordplay.
'in' indicates the answer is hidden within the clue.
'SCABIES' can be found hidden inside 'ones cab ie scratchy'.
(Other definitions for scabies that I've seen before include "Contagious skin infection" , "Contagious skin disease causing itching" , "Contagious skin disease that causes itching" , "rash complaint?" , "Skin disease - "The Itch"" .)