1
general::
Phrase(s): put to it
strained or exhausted. • Man, I’m really put to it! What a day! • John was put to it to get there on time.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Be confronted with a severe difficulty, as in I was put to it to finish this book on time. This usage is derived from the active sense of put to it, that is, "force or challenge someone to something." [c. 1600]
American Heritage Idioms