Without afterthought, cops now stick together (6)
I believe the answer is:
cohere
'stick together' is the definition.
(to cohere is to stick or fit together)
'without afterthought cops now' is the wordplay.
'without' is a deletion indicator.
'afterthought' becomes 'ps' (ps stands for postscript).
'now' becomes 'here' (I've seen this before).
'cops' with 'ps' taken out is 'co'.
'co'+'here'='COHERE'
(Other definitions for cohere that I've seen before include "Form a whole" , "Even; without jerks" , "Cling" , "Stick or hold together and resist separation" , "Fuse together" .)