Note creature lacking initial acceleration is smallest (7)
I believe the answer is:
minimal
'smallest' is the definition.
(similar in meaning)
'note creature lacking initial acceleration' is the wordplay.
I cannot quite see how this works, but
'note' could be 'minim' (type of musical note) and 'minim' is present in the answer.
'acceleration' could be 'a' (symbol used in Physics e.g. f=ma) and 'a' is present in the answer.
A single letter 'l' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'is' is the link.
Can you help me to learn more?
(Other definitions for minimal that I've seen before include "Token" , "Of a smallest amount" , "Least possible; negligible" , "barely worth considering" , "Very small, the least possible (7)" .)