A male singer looks odd in boater (8)
I believe the answer is:
baritone
'a male singer looks odd in boater' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for baritone that I've seen before include "solo voice" , "Male singer looks odd in boater" , "One who can sing" , "Adult male singing voice" , "Male voice between bass and tenor" .)