Could not find any definition of word "awant"
Usage examples of "awant".
But it seems that the old past tense of such a verb as awatâ, with a vowel immediately preceding the ending -tâ, was formed by nasal-infixion: Tolkien explicitly gave the past tense of the primitive verb as awantê (WJ:366.
In the case of a word like awantê, the rule that the second of two identical short vowels is lost could not apply (no **aw'ntê), for such loss does not occur immediately in front of a consonant cluster and the nasal-infixion has here produced a cluster nt.
The "final" Quenya form of awantê, namely oantë, is somewhat obscured because the group awa later became oa in Quenya but this change has nothing to do with the past tense formation.
The past tense is supposed to descend from awantê, evidently a nasal-infixed form of awatâ, and in Quenya, these forms regularly developed into oantë and auta, respectively.