Watchful as lazy employee reads tabloid at first (5)
I believe the answer is:
alert
'watchful' is the definition.
(similar in meaning)
'as lazy employee reads tabloid at first' is the wordplay.
'at first' indicates taking the first letters.
The initial letters of 'as lazy employee reads tabloid' is 'ALERT'.
(Other definitions for alert that I've seen before include "Awake, attentive" , "Vigilant - warning" , "Watchful and observant" , "Warning signal" , "Wide awake and watchful" .)