Beer they say makes you sicken (3)
I believe the answer is:
ail
'sicken' is the definition.
(I've seen this in another clue)
'beer they say' is the wordplay.
'beer' becomes 'ale' (type of beer).
'they say' indicates a 'sounds like' (homophone) clue.
'ale' sounds like 'AIL'.
'makes you' is the link.
(Other definitions for ail that I've seen before include "Sink" , "Cause to feel indisposed" , "Be the worse for wear" , "Be in poor health" , "Bother" .)