To kill time, I acted strangely (9)
I believe the answer is:
eradicate
'to kill' is the definition.
(eradicating is a kind of killing)
'time i acted strangely' is the wordplay.
'time' becomes 'era' (I've seen this before**).
'strangely' indicates an anagram.
'i'+'acted'='iacted'
'iacted' is an anagram of 'dicate'.
'era'+'dicate'='ERADICATE'
(Other definitions for eradicate that I've seen before include "Expunge" , "Destroy completely" , "Excise" , "Extinguish, wipe out" , "Scotch" .)