Sow page on the French book (5)
I believe the answer is:
plant
'sow' is the definition.
(I've seen this in another clue)
'page on the french book' is the wordplay.
'page' becomes 'p'.
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'the french' becomes 'la' ('the' in French).
'book' becomes 'nt' (New Testament).
'p'+'la'+'nt'='PLANT'
(Other definitions for plant that I've seen before include "Growing organism - industrial buildings" , "Factory - bit of vegetation" , "Factory; establish" , "Snooker shot; factory" , "Member of vegetable kingdom" .)