Fear of not having a right arm? (5)
I believe the answer is:
alarm
'fear' is the definition.
(alarm is a kind of fear)
'of not having a right arm?' is the wordplay.
'of not' becomes 'alar' (I can't justify this - if you can you should believe this answer much more).
'having' means one lot of letters go next to another.
'a right' says to take the final letters (I've seen 'right of' mean this (letter on the rightmost end of the word)).
The final letter of 'arm' is 'm'.
'alar'+'m'='ALARM'
Can you help me to learn more?
(Other definitions for alarm that I've seen before include "Warning siren" , "Alternative to reveille" , "Noise that wakes" , "Agitate" , "Security device" .)