Nothing in one plan revised by French leader (8)
I believe the answer is:
napoleon
'french leader' is the definition.
(I know this)
'nothing in one plan revised' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'in' means one lot of letters goes inside another.
'revised' indicates an anagram.
'one'+'plan'='oneplan'
'oneplan' with letters rearranged gives 'napleon'.
'o' going into 'napleon' is 'NAPOLEON'.
'by' is the link.
(Other definitions for napoleon that I've seen before include "Solo, perhaps" , "Ruler" , "Former French gold coin" , "Old French coin" , "French VIP" .)