Watching __; Carefully and Closely Studying

This page is the CodyCross answer for the clue below from Circus, Group 100, Puzzle 4 (Philip Astley).

Question is: Watching __; Carefully and Closely Studying

and the answer is: LIKEAHAWK

Word Meaning:

LIKE A HAWK — (simile) With particular vigilance or attention, implying sharp vision.

Definitions from Wiktionary.