Terrible, and not initially legal (5)
I believe the answer is:
awful
'terrible' is the definition.
(I know that terrible can be written as awful)
'not initially legal' is the wordplay.
'not initially' means to remove the first letter.
'legal' becomes 'lawful' (associated in meaning).
'lawful' with its first letter taken away is 'AWFUL'.
'and' is the link.
(Other definitions for awful that I've seen before include "Horrible" , "Really terrible, ghastly" , "Very poor" , "Really terrible, deplorable" , "shocking" .)