How timepiece thief remains vigilant? (5,5)

'vigilant?' is the definition.
I know nothing about this answer so I can't judge whether this works.

'how timepiece thief remains' is the wordplay.
I cannot really understand how this works, but
'timepiece' could be 'watch' (watch is a kind of timepiece) and 'watch' is found in the answer.
'remains' could be 'keeps' (keeping is a kind of remaining) and 'keeps' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...

Can you help me to learn more?