Not so awful that it stops you in your tracks? (8)
I believe the answer is:
passable
'stops you in your tracks?' is the definition.
I can't tell whether this defines the answer.
'not so awful that it' is the wordplay.
I cannot really see how this works, but
'so' could be 'as' (eg 'not as tall as me' means 'not so tall as me') and 'as' is found within the answer.
'it' could be 'sa' (old-fashioned abbreviation for sex appeal) and 'sa' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for passable that I've seen before include "Merely satisfactory" , "examinations should be!" , "Fair" , "not hogging the road" , "Barely adequate" .)