It sails from Oslo, perhaps, and Peterhead (5)
I believe the answer is:
sloop
'it sails' is the definition.
The definition suggests a singular noun which matches the answer.
'oslo perhaps and peterhead' is the wordplay.
'perhaps' is an anagram indicator.
'and' means one lot of letters go next to another.
'peterhead' becomes 'p' (head letter of 'peter').
'oslo' is an anagram of 'sloo'.
'sloo'+'p'='SLOOP'
'from' is the link.
Can you help me to learn more?
(Other definitions for sloop that I've seen before include "Type of sailing boat" , "One-masted sailing ship" , "Sailboat" , "Single-masted sailing vessel" , "one going to sea" .)