Declared men might have a misleading appearance (5)
I believe the answer is:
guise
'appearance' is the definition.
(guise is a kind of appearance)
'declared men' is the wordplay.
'declared' shows a homophone (sound like).
'men' becomes 'guys' (guy can informally mean a man).
'guys' sounds like 'GUISE'.
'might have a misleading' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for guise that I've seen before include "Mask" , "Show" , "Shape; pretence" , "Semblance; likeness" , "Demeanour" .)