You can always get a drink out of them! (4)
I believe the answer is:
mugs
'always get a drink out of them' is the definition.
I can't tell whether this definition defines the answer.
'you' is the wordplay.
I cannot really understand how this works, but
'you' could be 'u' (commonly used in online communication) and 'u' is found in the answer.
The remaining letters 'mgs' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'can' is the link.
Can you help me to learn more?
(Other definitions for mugs that I've seen before include "Cups without saucers" , "Gullible people" , "Faces (sl.)" , "Robs with the threat of violence" , "Cups; dupes" .)