Seat must have top class cover — a logical way to think (1,10)
I believe the answer is:
a posteriori
'a logical way to think' is the definition.
(as in a posteriori reasoning)
'seat must have top class cover' is the wordplay.
I cannot really see how this works, but
'seat' could be 'posterior' (synonyms) and 'posterior' is found within the answer.
'top' could be 'ai' (I've seen this in other clues) and 'ai' is found in the leftover letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for a posteriori that I've seen before include "discovered from experience" , "empiricism" , "afterthought" , "affected by experience" , "With hindsight" .)