Name that blue flag (5)
I believe the answer is:
peter
'name that blue flag' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'name that blue flag' is the wordplay.
'name' becomes 'Pet'.
'that blue flag' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'pet'+'er'='PETER'
Can you help me to learn more?
(Other definitions for peter that I've seen before include "Boy's name - safe" , "Sir - - Ustinov" , "Cephas" , "Blue -, ship's flag" , "Man's name" .)