Perfume is despatched, say (5)
I believe the answer is:
scent
'perfume' is the definition.
(I know that perfume can be written as scent)
'despatched say' is the wordplay.
'despatched' becomes 'sent' (I've seen this before).
'say' indicates a 'sounds like' (homophone) clue.
'sent' sounds like 'SCENT'.
'is' is the link.
(Other definitions for scent that I've seen before include "Number of clues" , "Trail" , "Pleasant smell" , "Get wind of" , "Track; aroma" .)