The most common and most likely answer to this crossword clue is the 6 letter word SITTER
I've seen this crossword clue in Financial Times
S
I
T
T
E
R
More clues leading to the result SITTER
Buddy explains!

The straight part
We know that "Model/one rarely missed?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case model/one rarely missed? = sitter.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 SITTER mean?
SITTER noun- Someone who sits, e.g. for a portrait.
- One employed to watch or tend something; a babysitter, housesitter, petsitter, etc.
- A participant in a séance.
- A broody hen.
- A very easy scoring chance.