Wiktionary
act up to
vb. To equal in action; to fulfill in practice.
Usage examples of "act up to".
He may have as strong a sense of what would be right, as you can have, without being so equal, under particular circumstances, to act up to it.
He haggled long about the price, for form's sake, to act up to his part as Nicholas Korpanoff, a plain merchant of Irkutsk.
That no man can ever act up to the pure idea of virtue does not in the least prove the chimerical nature of that concept.