Alexander's efforts to unite all of the Scots, and his concern for their welfare, made him the standard for his successors to emulate.
I think 'made him the standard' means definition 11-13. Then what is 'for his successors to emulate'? Do 'for his successors' and 'to emulate' just modify noun complement 'standard' respectively? Does 'for somebody to do something' have its own meaning?
Alexander's efforts to unite all of the Scots, and his concern for their welfare, made him the standard for his successors to emulate ___ .
"Him" is direct object of "made" and "the standard for his successors to emulate" is objective predicative complement.
"For his successors to emulate" is best analysed as an infinitival relative clause modifying "standard", where the relativised element is object of "emulate", as marked by the '___' notation.
Infinitival relative clauses typically have a modal meaning comparable to that expressed by "can" or "should". Compare here "the standard that his successors could/should emulate".
