I must stop tosser spinning yarns (7)
I believe the answer is:
stories
'yarns' is the definition.
('story' can be a synonym of 'yarn')
'i must stop tosser spinning' is the wordplay.
'must stop' means one lot of letters goes inside another (stopping can mean blocking a gap).
'spinning' indicates anagramming the letters.
'tosser' with letters rearranged gives 'stores'.
'i' placed into 'stores' is 'STORIES'.
(Other definitions for stories that I've seen before include "For example, scoops" , "See 21" , "Lies" , "See 12" , "Floors" .)