Those that shoot back will be comfortable (4)
I believe the answer is:
snug
'be comfortable' is the definition.
(similar in meaning)
'those that shoot back' is the wordplay.
'those' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
'that shoot' becomes 'gun' (I've seen this before).
'back' says the letters should be written in reverse.
'gun' backwards is 'nug'.
's'+'nug'='SNUG'
'will' acts as a link.
Can you help me to learn more?
(Other definitions for snug that I've seen before include "Close-fitting and cosy" , "Small bar in pub - warm and comfortable" , "Close fitting but comfortable" , "Bar-parlour" , "joiner" .)