Large omen gets broadcast - that's sharp (5)
I believe the answer is:
lemon
'sharp' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'large omen gets broadcast' is the wordplay.
I cannot really understand how this works, but
'large' could be 'l' (eg in clothes sizes) and 'l' is located in the answer.
an anagram of 'omen' is 'emon' which is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for lemon that I've seen before include "source of juice" , "A fruit; a worthless item" , "Dab" , "Defective object" , "Melon (anag)" .)