Old fogey to rage about source of expensive body spray (9)
I believe the answer is:
deodorant
'body spray' is the definition.
'old fogey to rage about source of expensive' is the wordplay.
'old fogey' becomes 'dodo' (both can refer to an old-fashioned person).
'to rage' becomes 'rant'.
'about' means one lot of letters goes inside another.
'source of' suggests taking the first letters.
The initial letter of 'expensive' is 'e'.
'dodo'+'rant'='dodorant'
'dodorant' placed around 'e' is 'DEODORANT'.
(Other definitions for deodorant that I've seen before include "for keeping smells away" , "Air-freshener" , "hum suppressor" , "Underarm spray, perhaps" , "Remover of smells" .)