One staggering around in Ostend, endlessly? (3)
I believe the answer is:
sot
'one staggering' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'around in ostend endlessly?' is the wordplay.
'around' becomes 'o' (a round letter).
'in' is an insertion indicator.
'ostend endlessly?' becomes 'st' (I can't explain this - if you can you should believe this answer much more).
'o' inserted inside 'st' is 'SOT'.
Can you help me to learn more?
(Other definitions for sot that I've seen before include "One's often intoxicated" , "Lush" , "A chronic drinker" , "Toper" , "drunk" .)