Bag endless grouse (4)
I believe the answer is:
grip
'bag' is the definition.
(type of travelling bag)
'endless grouse' is the wordplay.
'endless' means to remove the last letter.
'grouse' becomes 'gripe' (synonyms).
'gripe' with its last letter taken away is 'GRIP'.
(Other definitions for grip that I've seen before include "Ditch" , "Take firm hold of travelling bag?" , "Grab" , "Purchase" , "Grasp securely" .)