Efficient (7)
'efficient' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for able that I've seen before include "Having the ability to do something" , "As capable as a mariner" , "Competent, having ability" , "... was I ere I saw Elba (palindrome)" , "With the required capacities" .)
'efficient' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for capable that I've seen before include "Of a person, competent" , "Efficient" , "Able, proficient" , "accomplished" , "'Clever, able (7)'" .)