Lookalike at party feeling depressed and poorly treated (6)
I believe the answer is:
double
'lookalike' is the definition.
(I've seen this before)
'party feeling depressed and poorly treated' is the wordplay.
I cannot really see how this works, but
'party' could be 'do' (do is a kind of party) and 'do' is present in the answer.
This explanation may well be incorrect...
'at' is the link.
Can you help me to learn more?
(Other definitions for double that I've seen before include "Person who says one thing and does another" , "Designed for two users" , "Twice - bent over - run" , "Bed for two people" , "Increase twofold" .)