Dignify magnificent space first (7)
I believe the answer is:
ennoble
'dignify' is the definition.
(I know that dignify can be written as ennoble)
'magnificent space first' is the wordplay.
'magnificent' becomes 'noble' (I've seen this before).
'space' becomes 'en' (in printing, a space as wide as a letter 'n').
'first' is a charade indicator (letters next to each other).
'noble' after 'en' is 'ENNOBLE'.
(Other definitions for ennoble that I've seen before include "Elevate in rank" , "Aggrandise" , "Raise status" , "Exalt" , "Bestow peerage on" .)