Completely circle a Scottish town (5)
I believe the answer is:
alloa
'scottish town' is the definition.
(Alloa is a town in Scotland)
'completely circle a' is the wordplay.
'completely' becomes 'all' (synonyms).
'circle' becomes 'O' (O is a circle).
'all'+'o'+'a'='ALLOA'
(Other definitions for alloa that I've seen before include "Town built" , "Central Scottish town" , "Athletic club" , "A few thousand Scots" , "place in Scotland" .)