It's about saint, not as wakeful (8)
I believe the answer is:
restless
'wakeful' is the definition.
(I've seen this before)
'it's about saint not as' is the wordplay.
'it's about' becomes 're' (regarding).
'saint' becomes 'st' (abbreviation).
'not as' becomes 'less' (eg 'not as tall' means 'less tall').
're'+'st'+'less'='RESTLESS'
(Other definitions for restless that I've seen before include "Fidgety - unable to sleep" , "Ill at ease" , "Not relaxed, unsettled" , "Uneasy and agitated" , "Constantly active" .)