The most common and most likely answer to this crossword clue is the 8 plus 6 letter word DOGGEREL VERSES
D
O
G
G
E
R
E
L
V
E
R
S
E
S
Buddy explains!
The straight part
We know that "they have little substance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they have little substance = doggerel verses.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.