Severely modified trains using little energy? (12)
I believe the answer is:
astringently
'severely' is the definition.
Both the definition and answer are adverbs.
Maybe you can see a link between them that I can't see?
'modified trains using little energy?' is the wordplay.
I cannot really understand how this works, but
an anagram of 'trains' is 'astrin' which is within the answer.
'little' could be 'l' (abbreviation for little) and 'l' is located in the answer.
'energy?' could be 'e' (physics symbol as in E=mc2) and 'e' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for astringently that I've seen is " with invigorating effect".)