Axe thus destroyed drain (7)
I believe the answer is:
exhaust
'drain' is the definition.
(drain can mean to tire or exhaust)
'axe thus destroyed' is the wordplay.
'destroyed' indicates an anagram.
'axe'+'thus'='axethus'
'axethus' is an anagram of 'EXHAUST'.
(Other definitions for exhaust that I've seen before include "Deplete" , "Drain completely" , "get everything out of" , "Burnt gases are discharged here" , "Pipe to take away car fumes" .)