Even revelry is empty lately, in a weird way (6)
I believe the answer is:
eerily
'in a weird way' is the definition.
(I've seen this in another clue)
'even revelry is empty lately' is the wordplay.
'even' indicates alternate letters (letters in even-numbered positions are used).
'empty' suggests removing the centre.
'lately' with its middle removed is 'ly'.
'revelry'+'is'='revelryis'
The alternating letters of 'revelryis' are 'eeri'.
'eeri'+'ly'='EERILY'
(Other definitions for eerily that I've seen before include "how to seem frightening" , "in a disturbing way" , "alarmingly" , "In spooky or ghostly manner" , "In strange or unearthly way" .)