Will old wife be superficial? (7)
I believe the answer is:
shallow
'be superficial?' is the definition.
('shallow' can be similar in meaning to 'superficial')
'will old wife' is the wordplay.
'will' becomes 'shall' (synonyms).
'old' becomes 'o' (abbreviation).
'wife' becomes 'w' (abbreviation).
'shall'+'o'+'w'='SHALLOW'
(Other definitions for shallow that I've seen before include "incapable of serious thought" , "Of waters, not deep" , "Of water, not deep" , "Superficial" , "Lacking depth" .)