Toil until a man builds a large company (13)
I believe the answer is:
multinational
'a large company' is the definition.
(I've seen this before)
'toil until a man builds' is the wordplay.
'builds' indicates an anagram (I've seen 'built' mean this).
'toil'+'until'+'a'+'man'='toiluntilaman'
'toiluntilaman' anagrammed gives 'MULTINATIONAL'.
(Other definitions for multinational that I've seen before include "Crossing country borders" , "big business" , "Large company" .)