Virginia finds cover reasonable (5)
I believe the answer is:
valid
'reasonable' is the definition.
('valid' is associated in meaning with 'reasonable')
'virginia finds cover' is the wordplay.
'virginia' becomes 'va' (US state abbreviation).
'finds' means one lot of letters go next to another.
'cover' becomes 'lid' (lid is a kind of cover**).
'va'+'lid'='VALID'
(Other definitions for valid that I've seen before include "Legally acceptable and sound" , "Sound and to the point, also legal" , "Well-grounded" , "Sound, well-based" , "Still legally acceptable" .)