Outlaw putting collar up (3)
I believe the answer is:
ban
'outlaw' is the definition.
(I've seen this before)
'collar up' is the wordplay.
'collar' becomes 'nab' (both can mean to catch a person).
'up' is a reversal indicator (in down clue: letters go upwards).
'nab' written backwards gives 'BAN'.
'putting' is the link.
(Other definitions for ban that I've seen before include "outlaw" , "'Forbid, prohibit (3)'" , "Stop" , "the calling of young vassals" , "Embargo" .)