Former partner getting page and edition enlarged (8)
I believe the answer is:
expanded
'enlarged' is the definition.
(similar in meaning)
'former partner getting page and edition' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'getting' means one lot of letters go next to another.
'page' becomes 'p'.
'edition' becomes 'ed'.
'ex'+'p'+'and'+'ed'='EXPANDED'
(Other definitions for expanded that I've seen before include "Widened" , "Grew in extent" , "Amplified, spread out" , "Sort of polystyrene" , "Spread out, enlarged" .)