The most common and most likely answer to this crossword clue is the 7 letter word KIT-CAT
I've seen this crossword clue in Financial Times
K
I
T
-
C
A
T
Buddy explains!
The straight part
We know that "Club" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case club = kit-cat.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 KIT-CAT mean?
KIT-CAT noun- A short portrait, measuring 28 or 29 by 36 inches, less than half-length, but including the hands.