Henry maintains somewhat upper-class routine (8)
I believe the answer is:
habitual
'routine' is the definition.
(synonyms)
'henry maintains somewhat upper-class' is the wordplay.
'henry' becomes 'hal' (short for Henry).
'maintains' is an insertion indicator.
'somewhat' becomes 'a bit' (a bit).
'upper-class' becomes 'u' (similar in meaning).
'abit'+'u'='abitu'
'hal' going around 'abitu' is 'HABITUAL'.
(Other definitions for habitual that I've seen before include "Common" , "Traditional" , "Chronic" , "set" , "Like a routine" .)