Forced to rise, being directed across sierra (7)
I believe the answer is:
rousted
'forced to rise' is the definition.
(roust can mean to rouse or force to get up)
'directed across sierra' is the wordplay.
I cannot quite understand how this works, but
'sierra' could be 's' (phonetic alphabet: alpha, bravo, charlie etc.) and 's' is located in the answer.
'directed' could be 'routed' (routing is a kind of directing) and 'routed' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'being' acts as a link.
(Another definition for rousted that I've seen is " Stirred up".)