Weapons kept up one's sleeve? (4)
I believe the answer is:
arms
'weapons' is the definition.
('arm' can be a synonym of 'weapon')
'up one's sleeve?' is the wordplay.
'up' becomes 'ar' (I can't explain this - if you can you should give a lot more credence to this answer).
'one's' becomes 'me's' (a setter might use 'one' to humourously mean 'me').
'sleeve?' means to remove the middle letters (I've seen 'sleeves' mean this (sleeve can mean the outside letters)).
'mes' with its centre removed is 'ms'.
'ar'+'ms'='ARMS'
'kept' acts as a link.
Can you help me to learn more?
(Other definitions for arms that I've seen before include "Equips for war" , "Provides with weapons" , "See 11" , "Members" , "Weapons and limbs" .)