Current queue should finish, being efficient (11)
I believe the answer is:
streamlined
'efficient' is the definition.
('streamlined' can be similar in meaning to 'efficient')
'current queue should finish' is the wordplay.
'current' becomes 'stream' ('stream' can be a synonym of 'current'**).
'queue' becomes 'line' (I've seen this before).
'finish' indicates one should take the final letters.
The last letter of 'should' is 'd'.
'stream'+'line'+'d'='STREAMLINED'
'being' acts as a link.
(Other definitions for streamlined that I've seen before include "Aerodynamic" , "Designed to reduce wind resistance" , "Designed for smooth flow" , "Of sleek appearance" , "Shaped for speed" .)