The most common and most likely answer to this crossword clue is the 5 letter word SOCLE
I've seen this crossword clue in The Times
S
O
C
L
E
Buddy explains!
The straight part
We know that "Plinth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case plinth = socle.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 SOCLE mean?
SOCLE noun- A low plinth or pedestal used to display a statue or other artwork.
- A plain face or plinth at the foot of a wall.
- The sum of the minimal normal submodules of a given R-module of a given ring R.
- The subgroup generated by the minimal normal subgroups of a given group.