Lay out section with page having margin (5)
I believe the answer is:
spend
'lay out' is the definition.
(I've seen this in another clue)
'section with page having margin' is the wordplay.
'section' becomes 's' (legal abbreviation).
'with' says to put letters next to each other.
'page' becomes 'p'.
'having' is a charade indicator (letters next to each other).
'margin' becomes 'end'.
's'+'p'+'end'='SPEND'
(Other definitions for spend that I've seen before include "Pay out (on goods)" , "Pass (time) in a specified way" , "Pay out (money)" , "Blow" , "While away" .)