Composer with hesitation put away gun (7)
I believe the answer is:
holster
'put away gun' is the definition.
(to put a gun in a holster)
'composer with hesitation' is the wordplay.
'composer' becomes 'holst' (Gustav Holst).
'with' means one lot of letters go next to another.
'hesitation' becomes 'er' (sound used when hesitating).
'holst'+'er'='HOLSTER'
(Other definitions for holster that I've seen before include "Gun holder" , "Gun-holder" , "Revolver' cover" , "Gun-case" , "Pistol sheath" .)