Regular soldier's garb (7)
I believe the answer is:
uniform
'garb' is the definition.
(uniforming is a kind of garbing)
'regular soldier's' is the wordplay.
I cannot quite see how this works, but
'soldier' could be 'rm' (Royal Marine) and 'rm' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for uniform that I've seen before include "follower of tango on the radio?" , "Identifying clothing" , "Tunic; even" , "Same - suit" , "Services' clothing" .)