Decided to cite a justification for limiting speed (8)
I believe the answer is:
emphatic
'decided' is the definition.
(thesaurus)
'cite a justification for limiting speed' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
'speed' could be 'mph' (miles per hour) and 'mph' is present in the answer.
an anagram of 'cite' is 'etic' which is present in the remaining letters.
No letters remain.
This explanation may well be incorrect...
'to' is the link.
Can you help me to learn more?
(Other definitions for emphatic that I've seen before include "Able to experience another's feelings" , "Forceful and definite" , "For sure" , "Forceful in expression" , "Expressing oneself with vigour and conviction" .)