Using excessive force to disperse oil in the air-shaft (7)
I believe the answer is:
violent
'using excessive force' is the definition.
(I've seen this before)
'disperse oil in the air-shaft' is the wordplay.
'disperse' is an anagram indicator (I've seen 'disperses' mean this).
'in the' is an insertion indicator.
'air-shaft' becomes 'vent' (I can't explain this - if you can you should believe this answer much more).
'oil' is an anagram of 'iol'.
'iol' inserted inside 'vent' is 'VIOLENT'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for violent that I've seen before include "Intensely forcible" , "Immoderate" , "Using extreme physical force" , "Using much force" , "Wild - not evil (anag)" .)