Drive new train without any doubt (3,7)
I believe the answer is:
for certain
'drive new train without any doubt' is the definition.
I can't judge whether this definition defines the answer.
'drive new train without' is the wordplay.
'drive' becomes 'force' (synonyms).
'new' indicates anagramming the letters.
'without' indicates putting letters inside.
'train' with letters rearranged gives 'rtain'.
'force' going within 'rtain' is 'FOR CERTAIN'.
Can you help me to learn more?
(Other definitions for for certain that I've seen before include "without a doubt" , "definitely" , "surely" , "Assuredly" .)