Ken? Ken's first at this time (4)
I believe the answer is:
know
'ken?' is the definition.
(I've seen this before)
'ken's first at this time' is the wordplay.
'ken's first' becomes 'k' (1st letter of 'ken').
'at this time' becomes 'now' (at the present time).
'k'+'now'='KNOW'
(Other definitions for know that I've seen before include "A Channel port, type of sole" , "Ken" , "Be familiar with" , "Understand" , "Be aware of (something)" .)