Set to secure arrest? That’s credible (7)
I believe the answer is:
tenable
'credible' is the definition.
(thesaurus)
'set to secure arrest?' is the wordplay.
'set' becomes 'tele' (I can't justify this - if you can you should believe this answer much more).
'to secure' is an insertion indicator (inserted letters are secured inside).
'arrest?' becomes 'nab' ('nab' can be a synonym of 'arrest').
'tele' enclosing 'nab' is 'TENABLE'.
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for tenable that I've seen before include "possible to maintain" , "Late Ben (anag.)" , "Well-founded" , "okay as regards defence" , "Able to be defended against attack or objection" .)