End of sleeping? Wake up and grumble (6)
I believe the answer is:
grouse
'grumble' is the definition.
(thesaurus)
'end of sleeping? wake up' is the wordplay.
'end of' indicates one should take the final letters.
'wake up' becomes 'rouse' (I've seen this before).
The final letter of 'sleeping' is 'g'.
'g'+'rouse'='GROUSE'
'and' is the link.
(Other definitions for grouse that I've seen before include "Plump game bird" , "Bird - complaint" , "Gripe; game bird" , "Game bird - beef" , "Bellyache" .)