The most common and most likely answer to this crossword clue is the 9 letter word GALLIPOLI
I've seen this crossword clue in The Times
G
A
L
L
I
P
O
L
I
More clues leading to the result GALLIPOLI
- Nettle I chop back on island peninsula
- I see rifle almost raised in WWI campaign
- I see endless loot around failed invasion site
- Upset, I behold endless plundering in WWI battle site
- Medicine served up in prison, one in disastrous campaign
- US soldier capturing every current petty officer left in 11 battleground
- Largely Frenchcampaign of WW1
- Many died here of French disease, losing both feet
- I see plunder largely reflected in battle site
- Not blab about grain-store sacking on comeback campaign
Buddy explains!
The straight part
We know that "peninsula" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case peninsula = gallipoli.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.