Heard chaps' appearance (5)
I believe the answer is:
guise
'appearance' is the definition.
(guise is a kind of appearance)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for guise that I've seen before include "Mask" , "Appearance, semblance" , "Demeanour" , "Semblance; likeness" , "Shape; pretence" .)