New sleeping-place mostly occupied by English commando (5,5)
I believe the answer is:
green beret
'commando' is the definition.
(I've seen this before)
'new sleeping-place mostly occupied by english' is the wordplay.
'new' becomes 'green'.
'sleeping-place' becomes 'berth'.
'mostly' means to remove the last letter.
'occupied by' indicates putting letters inside.
'english' becomes 'e' (abbreviation).
'berth' with its last letter taken off is 'bert'.
'bert' enclosing 'e' is 'beret'.
'green'+'beret'='GREEN BERET'
(Other definitions for green beret that I've seen before include "British commando (colloq.)" , "Member of fighting unit" , "fighter in raiding unit" , "soldier" .)