Spoken during last half of royal castle (4)
I believe the answer is:
oral
'spoken' is the definition.
(similar in meaning)
'half of royal castle' is the wordplay.
'half of' indicates taking half.
'royal castle' becomes 'balmoral' (I've seen this before).
'balmoral' with half the letters taken is 'ORAL'.
'during last' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for oral that I've seen before include "'Spoken, not written (4)'" , "By word of mouth (4)" , "Concerning the mouth" , "Relating to speech" , "Of the voice" .)