Birds consuming beer wildly in extremes of grossness (6)
I believe the answer is:
grebes
'birds' is the definition.
(grebe is a kind of bird)
'beer wildly in extremes of grossness' is the wordplay.
'wildly' indicates an anagram.
'in' indicates putting letters inside.
'extremes of' suggests removing the centre (only the letters at the extremes of the word).
'grossness' with its middle removed is 'gs'.
'beer' with letters rearranged gives 'rebe'.
'rebe' put within 'gs' is 'GREBES'.
'consuming' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for grebes that I've seen before include "Small diving birds" , "Small sea-birds" , "Crested waterfowl" , "Diving waterbirds" .)