Take a dekko — and see all right (4)
I believe the answer is:
look
'take a dekko' is the definition.
(dekko can informally mean a glance)
'see all right' is the wordplay.
'see' becomes 'lo' (archaic word meaning 'look!').
'all right' becomes 'ok' ('ok' can be a synonym of 'all right').
'lo'+'ok'='LOOK'
'and' is the link.
(Other definitions for look that I've seen before include "Peer" , "Inspect" , "Direct one's gaze towards" , "Behold" , "Search (with the eyes)" .)