Trace outrigger's front and stern (5)
I believe the answer is:
odour
'trace' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'outrigger's front and stern' is the wordplay.
'front' indicates taking the first letters.
'and' is a charade indicator (letters next to each other).
'stern' becomes 'dour' (I've seen this in another clue).
The first letter of 'outriggers' is 'o'.
'o'+'dour'='ODOUR'
Can you help me to learn more?
(Other definitions for odour that I've seen before include "Stink" , "Smell, redolence" , "Regard" , "Aroma, smell" , "Small, aroma" .)