Select smart response, finally putting nothing in (6)
I believe the answer is:
choice
'select' is the definition.
('choice' can be a synonym of 'select')
'smart response finally putting nothing in' is the wordplay.
I cannot really see how this works, but
'nothing' could be 'o' (looks like zero - 0) and 'o' is located in the answer.
'smart' could be 'chic' ('chic' can be a synonym of 'smart') and 'chic' is present in the remaining letters.
A single letter 'e' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for choice that I've seen before include "Volition" , "Select" , "of superior quality" , "Best - selection" , "Plum" .)