Watch how things pan out as we detain criminal (4,3,3)
I believe the answer is:
wait and see
'watch how things pan out' is the definition.
(see what happens)
'as we detain criminal' is the wordplay.
'criminal' indicates anagramming the letters.
'as'+'we'+'detain'='aswedetain'
'aswedetain' is an anagram of 'WAIT AND SEE'.
(Other definitions for wait and see that I've seen before include "Bide one's time" , "Take no action and watch how events pan out" , "Be patient to find how things turns out" , "Reserve judgement until it happens" .)