Ruddy large number to correct (7)
I believe the answer is:
redraft
'correct' is the definition.
(thesaurus)
'ruddy large number' is the wordplay.
'ruddy' becomes 'red' (synonyms).
'large number' becomes 'raft' (I've seen this in another clue).
'red'+'raft'='REDRAFT'
'to' is the link.
(Other definitions for redraft that I've seen before include "Altered document" , "Make a copy" , "second edition" , "Produce a new version of a document" , "Sketch a new plan" .)