First dish, in more than one instance, is cooked too long (8)
I believe the answer is:
overdone
'is cooked too long' is the definition.
(I've seen this before)
'first dish in more than one' is the wordplay.
'first dish' becomes 'd' (1st letter of 'dish').
'in' indicates putting letters inside.
'more than' becomes 'over' (eg over 100 is more than 100).
'over'+'one'='overone'
'd' placed inside 'overone' is 'OVERDONE'.
'instance' acts as a 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 overdone that I've seen before include "Cooked too much or carried too far" , "Exaggerated; cooked too much" , "really a bit much!" , "Cooked to excess" , "Exaggerated; burnt (meat)" .)