Sparing the endless break ends uneasily (7)
I believe the answer is:
thrifty
'sparing' is the definition.
(similar in meaning)
'the endless break ends uneasily' is the wordplay.
'endless' means to remove the last letter.
'break' becomes 'rift' (rift can mean a break or opening).
'ends' suggests the final letters.
The last letter of 'uneasily' is 'y'.
'the' with its last letter taken away is 'th'.
'th'+'rift'+'y'='THRIFTY'
(Other definitions for thrifty that I've seen before include "Frugal - economical" , "Sparing" , "Careful and diligent in the use of resources" , "Not extravagant" , "Careful with money" .)