Bar is quiet at the back (5)
I believe the answer is:
shaft
'bar' is the definition.
(thesaurus)
'quiet at the back' is the wordplay.
'quiet' becomes 'sh'.
'at' says to put letters next to each other.
'the back' becomes 'aft' (I've seen this before**).
'sh'+'aft'='SHAFT'
'is' is the link.
(Other definitions for shaft that I've seen before include "Beam - well" , "Ray (of sunlight)" , "Ray of light; treat unfairly" , "Ray (of light), access to mine" , "Aggressive remark" .)