The most common and most likely answer to this crossword clue is the 13 letter word FLAXEN-HAIRED
I've seen this crossword clue in Financial Times
F
L
A
X
E
N
-
H
A
I
R
E
D
Buddy explains!
The straight part
We know that "like 20" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case like 20 = flaxen-haired.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.