The most common and most likely answer to this crossword clue is the 6 letter word COEVAL
I've seen this crossword clue in The Guardian
C
O
E
V
A
L
Buddy explains!
The straight part
We know that "of same 14 or 16" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of same 14 or 16 = coeval.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 COEVAL mean?
COEVAL noun- Something of the same era.
- Somebody of the same age.
- Of the same age; contemporary.