A beer? It's almost closed! (4)
I believe the answer is:
ajar
'almost closed' is the definition.
(I've seen this in another clue)
'a beer?' is the wordplay.
'beer?' becomes 'jar' (I've seen this before).
'a'+'jar'='AJAR'
'it's' is the link.
(Other definitions for ajar that I've seen before include "It's nearly open" , "A little bit open, like door" , "Mourn" , "Not quite shut" , "near closing?" .)