Starts back, including you in some cloud (7)
I believe the answer is:
stratus
'some cloud' is the definition.
(stratus cloud is a kind of cloud)
'starts back including you' is the wordplay.
'back' says the letters should be written in reverse.
'including' indicates putting letters inside.
'you' becomes 'u' (I've seen this in other clues).
'starts' backwards is 'strats'.
'strats' going around 'u' is 'STRATUS'.
'in' is the link.
(Other definitions for stratus that I've seen before include "Grey cover" , "Cloud as a grey sheet" , "Sheet of low cloud" , "Cloud cover" , "Large dark low cloud" .)