Teases Stallone without justification (10)
I believe the answer is:
needlessly
'without justification' is the definition.
(I've seen this before)
'teases stallone' is the wordplay.
'teases' becomes 'needles' (I've seen this in another clue).
'stallone' becomes 'sly' (nickname for Sylvester Stallone).
'needles'+'sly'='NEEDLESSLY'
(Other definitions for needlessly that I've seen before include "Unnecessarily" , "without justification" , "without good reason" , "without any necessity" .)