The most common and most likely answer to this crossword clue is the 10 plus 6 letter word MIDDLE-AGE SPREAD
I've seen this crossword clue in The Guardian
M
I
D
D
L
E
-
A
G
E
S
P
R
E
A
D
More clues leading to the result MIDDLE-AGE SPREAD
- Form-filling associated with the pre-60s?
- After distance driven carrying theologian, padre’s changing spare tyre
- Page to study, when understanding former time period has caused unwanted fat
- . Some time in the past, padre blessed breadbasket
- A source of extra heft a long time ago – before the Christian Era?
- Waist problem Papa studied after a historical period
- Expanding corporation merged, deals paid off
- Spare tyre limp — grease added for repair
- New slide made GP study distribution in later life
Buddy explains!
The straight part
We know that "Spare tyre" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spare tyre = middle-age spread.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.