As usual, young and thickset (6)
I believe the answer is:
stocky
'thickset' is the definition.
(synonyms)
'as usual young' is the wordplay.
I cannot really see how this works, but
'usual' could be 'stock' (stock can mean usual or cliched) and 'stock' is found in the answer.
'young' could be 'y' and 'y' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for stocky that I've seen before include "Heavily-built" , "Short and sturdy" , "Of short and solid stature" , "Small and well built" , "Strongly-built" .)