Bar a beginner at all times (5)
I believe the answer is:
lever
'bar' is the definition.
(lever is a kind of bar)
'a beginner at all times' is the wordplay.
'a beginner' becomes 'l'.
'at all times' becomes 'ever' ('ever' can be a synonym of 'at all times').
'l'+'ever'='LEVER'
(Other definitions for lever that I've seen before include "Machine operator" , "Prize" , "Bar turning on a fulcrum" , "Prise using bar" , "Revel in moving bar" .)