Curiously wanting one less good qualification for mechanics (9)
I believe the answer is:
newtonian
'for mechanics' is the definition.
(Newtonian mechanics is an example)
'curiously wanting one less good' is the wordplay.
'curiously' indicates anagramming the letters.
'less' suggests deleting specific letters (less can mean minus).
'good' becomes 'g' (abbreviation).
'wanting'+'one'='wantingone'
'wantingone' with 'g' taken away is 'wantinone'.
'wantinone' is an anagram of 'NEWTONIAN'.
'qualification' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for newtonian that I've seen before include "using non-relativistic laws" , "of a famous mathematician" , "Relating to a famous English scientist" , "such a telescope?" .)