Guinness, perhaps, or a beer that's cold (4)
I believe the answer is:
alec
'guinness perhaps' is the definition.
I can't judge whether this defines the answer.
'a beer that's cold' is the wordplay.
'a beer' becomes 'ale' (type of beer).
'that's cold' becomes 'c' (eg on taps).
'ale'+'c'='ALEC'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for alec that I've seen before include "A smart . . . . is a know-all in lace" , "Guinness (a smart lad?)" , "Smart man?" , "Smart ..., he thinks he knows everything" , "Boy's name (a smart one?)" .)