Device to get one sitting up? (9)
I believe the answer is:
chairlift
'device to get one sitting up?' is the definition.
(device which lifts a sitting person up)
'device to get one' is the wordplay.
'device' becomes 'chair' (chair is a kind of device).
'to get one' becomes 'lift' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'chair'+'lift'='CHAIRLIFT'
(Other definitions for chairlift that I've seen before include "It moves people up" , "Transport for skiers" , "one taken in the mountains" , "help for skiers" , "mountain transport" .)