a-watchadv.

/əˈwɒtʃ/Etymology: a prep.1 + watch n.
the world > action or operation > safety > protection or defence > vigilance > [adverb]
1856 E. B. Browning vii. 291 As a dog a-watch for his master's foot.
This entry has not yet been fully updated (first published 1885; most recently modified version published online December 2018).