Smarten up pages around margin (5)
I believe the answer is:
primp
'smarten up' is the definition.
(I've seen this in another clue)
'pages around margin' is the wordplay.
'pages' becomes 'pp' (an abbreviation for page written twice).
'around' is an insertion indicator.
'margin' becomes 'rim' (both can mean something's edge).
'pp' placed around 'rim' is 'PRIMP'.
(Other definitions for primp that I've seen before include "Tidy" , "Titivate one's appearance" , "Make minor adjustments to one's appearance" , "Groom oneself elaborately" , "brush?" .)