A mere semblance, as the chaps said (5)
I believe the answer is:
'a mere semblance' is the definition.
'guise' can be an answer for 'semblance' (guise is a kind of semblance). I'm unsure of the 'a mere' bit.
'the chaps said' is the wordplay.
'the chaps' becomes 'guys' (both can mean men).
'said' shows a homophone (sound like).
'guys' is a homophone of 'GUISE'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for guise that I've seen before include "Shape; pretence" , "Mask" , "Appearance, semblance" , "General appearance" , "Demeanour" .)