Well-adapted, efficient, and thus pithy? Not initially (9)
I believe the answer is:
ergonomic
'well-adapted efficient' is the definition.
I can't judge whether this defines the answer.
'thus pithy? not initially' is the wordplay.
I cannot really see how this works, but
'thus' could be 'ergo' (I've seen this before) and 'ergo' is located in the answer.
'not' could be 'no' (negative) and 'no' is present in the answer.
The remaining letters 'mic' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'and' is the link.
Can you help me to learn more?
(Other definitions for ergonomic that I've seen before include "using biotechnology" , "Maximising efficiency" , "Designed for work efficiency" , "Designed for efficiency and comfort in the working environment" , "operating with maximum efficiency" .)