Frank sat right strangely (8)
I believe the answer is:
straight
'frank' is the definition.
(I've seen this before)
'sat right strangely' is the wordplay.
'strangely' indicates an anagram.
'sat'+'right'='satright'
'satright' anagrammed gives 'STRAIGHT'.
(Other definitions for straight that I've seen before include "square" , "Directly; neat" , "Sat right in unbending way" , "Plain-speaking" , "Not curved or bent" .)