Too small-time; that's clear (5)
I believe the answer is:
overt
'clear' is the definition.
(both can mean apparent or obvious)
'too small-time' is the wordplay.
'too small' becomes 'over' (I can't justify this - if you can you should believe this answer much more).
'time' becomes 't' (abbreviation).
'over'+'t'='OVERT'
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for overt that I've seen before include "not disguised" , "Open and observable" , "This is not hard to see" , "____ is able to be seen" , "Patent, evident" .)