Reasonable show (4)
I believe the answer is:
fair
I believe this clue is a double definition.
'reasonable' is the first definition.
(I know that reasonable can be written as fair)
'show' is the second definition.
(I know that fair is a type of show)
(Other definitions for fair that I've seen before include "Satisfactory" , "Unbiased, being light of skin" , "nothing special" , "Having light-coloured hair and skin" , "square" .)