First light paper, then stand up (7)
I believe the answer is:
sunrise
'first light' is the definition.
('sunrise' can be a synonym of 'first light')
'paper then stand up' is the wordplay.
'paper' becomes 'sun' (The Sun, UK newspaper).
'then' means one lot of letters go next to another.
'stand up' becomes 'rise' ('rise' can be a synonym of 'stand up').
'sun'+'rise'='SUNRISE'
(Other definitions for sunrise that I've seen before include "Day's beginning" , "What follows dawn" , "It's preceded by dawn" , "Type of industry" , "It gets the day off to a bright start" .)