Watch as diver secures approval (4,2)
I believe the answer is:
look on
'watch' is the definition.
(I've seen this before)
'diver secures approval' is the wordplay.
'diver' becomes 'loon' ('loon' can be a synonym of 'diver').
'secures' is an insertion indicator.
'approval' becomes 'ok' (OK is an example**).
'loon' going around 'ok' is 'LOOK ON'.
'as' is the link.
(Other definitions for look on that I've seen before include "Stand by watching, observe" , "Watch without becoming involved" , "Be a spectator, watch" , "Watch as observer - dont get involved" , "Be a spectator, observe" .)