The most common and most likely answer to this crossword clue is the 8 letter word STRAWMAN
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More clues leading to the result STRAWMAN
Buddy explains!
The straight part
We know that "he lacks substance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case he lacks substance = strawman.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does STRAWMAN mean?
STRAWMAN noun- The third party who makes a straw purchase for another person.
- A doll or scarecrow, particularly one stuffed with straw.
- An innocuous person or someone of nominal or lesser importance, as a front man or straw boss.
- An insubstantial concept, idea, endeavor or argument, particularly one deliberately set up to be weakly supported, so that it can be easily knocked down; especially to impugn the strength of any related or contrasted thing or idea.
- An outline serving as an initial proposal for a project, usually refined iteratively.
- To falsely attribute an insubstantial argument (a straw man argument) to another through direct declaration or indirect implication; to put words in someone's mouth.