No skinhead in the Ministry of Defence (3)
I believe the answer is:
mod
'ministry of defence' is the definition.
(abbreviation)
'no skinhead in' is the wordplay.
'no' becomes 'O' (O resembles 0).
'skinhead' becomes 'md' (I can't explain this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'o' put into 'md' is 'MOD'.
'the' is the link.
Can you help me to learn more?
(Other definitions for mod that I've seen before include "Rocker's rival?" , "Meeting of the Scottish" , "ministry" , "1960s teenager" , "Gaelic literary festival" .)