Dispatched about 100 for perfume (5)
I believe the answer is:
scent
'for perfume' is the definition.
(synonyms)
'dispatched about 100' is the wordplay.
'dispatched' becomes 'sent' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'100' becomes 'c' (Roman numeral).
'sent' placed around 'c' is 'SCENT'.
(Other definitions for scent that I've seen before include "Trail" , "Pleasant odour" , "Bouquet" , "Get wind of" , "Fragrance" .)