Get in shaken after one fire (6)
I believe the answer is:
ignite
'fire' is the definition.
(I've seen this before)
'get in shaken after one' is the wordplay.
'shaken' is an anagram indicator.
'after' means one lot of letters go next to another.
'one' becomes 'I' (Roman numeral).
'get'+'in'='getin'
'getin' with letters rearranged gives 'gnite'.
'gnite' put after 'i' is 'IGNITE'.
(Other definitions for ignite that I've seen before include "Swan constellation" , "Catch fire; provoke" , "Kindle Fire" , "Burn" , "Detonate" .)