Travellers gloomy, drinking beer? Quite the opposite (8)
I believe the answer is:
pilgrims
'travellers' is the definition.
(pilgrim is a kind of traveller)
'gloomy drinking beer? quite the opposite' is the wordplay.
I cannot really see how this works, but
'gloomy' could be 'grim' (I've seen this before) and 'grim' is found within the answer.
'beer?' could be 'pils' (Pilsner beer) and 'pils' is found in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
(Other definitions for pilgrims that I've seen before include "Travellers to sacred places" , "Slim prig (anag.)" , "Grim slip by religious travellers" , "Travellers to holy places" , "See 1" .)