Awful to have three keys (3)
I believe the answer is:
bad
'awful' is the definition.
(similar in meaning)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for bad that I've seen before include "Harmful" , "Stinking" , "Of poor quality" , "(Of food) decayed" , "SECOND HALF OF 16" .)