Fear of not having a right arm? (5)
I believe the answer is:
alarm
'fear' is the definition.
(alarm is a kind of fear)
'right arm?' is the wordplay.
'right' becomes 'al' (I can't explain this - if you can you should give a lot more credence to this answer).
'al'+'arm'='ALARM'
'of not having a' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
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" .)