Rum in fashion briefly, as are grapes (7)
I believe the answer is:
trodden
'as are grapes' is the definition.
(grapes are trodden on as part of wine-making)
'rum in fashion briefly' is the wordplay.
'rum' becomes 'odd' (I've seen this before).
'in' means one lot of letters goes inside another.
'fashion' becomes 'trend' (I've seen this before).
'briefly' means to remove the last letter.
'trend' with its last letter removed is 'tren'.
'odd' going inside 'tren' is 'TRODDEN'.
(Other definitions for trodden that I've seen before include "Trampled" , "Crushed under the feet" , "Footpaths are" , "Oppressed" , "Heavily walked upon" .)