Nut for old farm vehicle's ventilator (9,3)
I believe the answer is:
extractor fan
'nut' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'old farm vehicle's ventilator' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'farm vehicle' becomes 'tractor' (I've seen this in another clue).
'ventilator' becomes 'fan' (something which provides ventilation).
'ex'+'tractor'+'fan'='EXTRACTOR FAN'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for extractor fan that I've seen before include "Kitchen odour remover" , "Device to remove stale air or fumes" .)