Large number following daughter's plan (5)
I believe the answer is:
draft
'plan' is the definition.
(drafting is a kind of planning)
'large number following daughter's' is the wordplay.
'large number' becomes 'raft' (I've seen this in another clue).
'following' says to put letters next to each other.
'daughter' becomes 'd' (genealogical abbreviation).
'raft' put after 'd' is 'DRAFT'.
(Other definitions for draft that I've seen before include "Send" , "plan outlined" , "Preliminary drawing" , "Sketch - detachment of men" , "Outline or sketch" .)