A large member can create apprehension (5)
I believe the answer is:
alarm
'apprehension' is the definition.
(I've seen this in another clue)
'a large member' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'member' becomes 'arm' (member can mean a limb).
'a'+'l'+'arm'='ALARM'
'can create' is the 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 "Daunt" , "Alternative to reveille" , "Burglar deterrent" , "Frighten or startle" , "Unnerve" .)