Judgement of one lacking in awareness (8)
I believe the answer is:
sentence
'judgement' is the definition.
(sentence is a kind of judgement)
'one lacking in awareness' is the wordplay.
'one' becomes 'i' (Roman numeral).
'lacking in' suggests deleting specific letters.
'awareness' becomes 'sentience' (sentience is being aware or conscious).
'sentience' with 'i' taken away is 'SENTENCE'.
'of' acts as a link.
(Other definitions for sentence that I've seen before include "Group of words with verb" , "That which ends with a full stop" , "must come to a stop!" , "complete grammatical structure" , "Court decision on a grammatical structure" .)