Help for a case of scabies, I posture (10)
I believe the answer is:
assistance
'help' is the definition.
('assistance' can be a synonym of 'help')
'a case of scabies i posture' is the wordplay.
'case of' says to hollow out the word (remove centre letters) (outsides of).
'posture' becomes 'stance' (stance is a kind of posture**).
'scabies' with its middle taken out is 'ss'.
'a'+'ss'+'i'+'stance'='ASSISTANCE'
'for' is the link.
(Other definitions for assistance that I've seen before include "Support" , "Help" , "Aid" .)