Though on a false trail, all round is showing sense (8)
I believe the answer is:
rational
'is showing sense' is the definition.
I can't tell whether this definition defines the answer.
'though on a false trail all round' is the wordplay.
'though' becomes 'on' (I can't explain this - if you can you should believe this answer much more).
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'false' indicates an anagram.
'all round' means one lot of letters goes inside another.
'trail' is an anagram of 'rtial'.
'a' placed within 'rtial' is 'ratial'.
'on' put inside 'ratial' is 'RATIONAL'.
Can you help me to learn more?
(Other definitions for rational that I've seen before include "Consistent with logic" , "Able to reason" , "In accordance with logic" , "Based on reason or logic" , "Sane, based on logic" .)