Show approval: no dice at first (3)
I believe the answer is:
nod
'show approval' is the definition.
(I've seen this in another clue)
'no dice at first' is the wordplay.
'at first' says to take the initial letters.
The first letter of 'dice' is 'd'.
'no'+'d'='NOD'
(Other definitions for nod that I've seen before include "It's said to be as good as a wink" , "Cain left Eden for the Land of . . ." , "Acknowledge by gesture" , "Drowse" , "'A . . . is as good as a wink to a blind horse'" .)