In vogue, stalwart chat show participant? (5)
I believe the answer is:
guest
'chat show participant?' is the definition.
'in vogue stalwart' is the wordplay.
'in' indicates the answer is hidden within the clue.
'GUEST' can be found hidden inside 'vogue stalwart'.
(Other definitions for guest that I've seen before include "Customer of a hotel" , "Recipient of hospitality" , "Conjectured audibly" , "Visitant" , "Invited visitor" .)