To be sufficiently dressed is only reasonable (6)
I believe the answer is:
decent
This could be a double definition.
'to be sufficiently dressed' is the first definition.
'only reasonable' is the second definition.
'decent' can be an answer for 'reasonable' (I've seen this before). I'm unsure of the 'only' bit.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for decent that I've seen before include "Fitting; satisfactory" , "Nice" , "Kind of respectable" , "Morally respectable" , "Respectable; satisfactory" .)