Material that’s grand in fashionable shift (7)
I believe the answer is:
realign
'shift' is the definition.
'material that's grand in fashionable' is the wordplay.
'material' becomes 'real' ('real' is associated in meaning with 'material').
'that's grand' becomes 'g' ('G' can be a synonym of 'grand').
'in' means one lot of letters goes inside another.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
'g' placed into 'in' is 'ign'.
'real'+'ign'='REALIGN'
(Other definitions for realign that I've seen before include "Again order" , "Change position (of something)" , "Make new alliances" , "return to proper position" , "Apply" .)