Arab League is partially competent (4)
I believe the answer is:
able
'competent' is the definition.
(similar in meaning)
'arab league is partially' is the wordplay.
'is partially' says the answer is hidden in the clue.
'ABLE' is hidden within 'arab league'.
(Other definitions for able that I've seen before include "Having great proficiency or intelligence" , "showing talent" , "Competent as, say, sailor" , "Qualified - expert" , "Adept" .)