Most efficient cycling boards (6)
I believe the answer is:
tables
'boards' is the definition.
('table' can be a synonym of 'board')
'most efficient cycling' is the wordplay.
I cannot really understand how this works, but
'efficient' could be 'able' (I've seen this before) and 'able' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tables that I've seen before include "Sets of data arranged in rows and columns" , "Lists of figures arranged in columns" , "Turn these to reverse the situation in your own favour" , "Sets of facts and figures in columns and rows" , "Turn these to gain the advantage" .)