Actors transformed fuel into purgative (6,3)
I believe the answer is:
castor oil
'purgative' is the definition.
(I've seen this before)
'actors transformed fuel' is the wordplay.
'transformed' indicates anagramming the letters.
'fuel' becomes 'oil' (I've seen this before).
'actors' with letters rearranged gives 'castor'.
'castor'+'oil'='CASTOR-OIL'
'into' is the link.
(Other definitions for castor oil that I've seen before include "Some help to clear out inside" , "medicine?" , "Medicinal stuff" , "Purgative from African shrub" , "move furniture quietly?" .)