Swimming competition on the banks of Gallipoli peninsula (4)
I believe the answer is:
gala
'swimming competition' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for gala that I've seen before include "Special performance" , "Public festivity" , "A festive occasion, perhaps of sporting nature" , "A show of charity" , "Fête" .)