Silly person, Oscar, leaving tower at first sign of panic (5)

I believe the answer is:

twerp

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'silly person' is the definition.
(twerp can mean a silly or annoying person)

'oscar leaving tower at first sign of panic' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'leaving' suggests deleting specific letters.
'at' means one lot of letters go next to another.
'first sign of panic' becomes 'p' (I can't justify this - if you can you should believe this answer much more).
'tower' with 'o' removed is 'twer'.
'twer'+'p'='TWERP'

Can you help me to learn more?

(Other definitions for twerp that I've seen before include "ass" , "Nitwit" , "Silly person" , "Twit" , "Idiot" .)

I've seen this clue in The Times.

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