Being indomitable, I deserve any break (5-3-3)
I believe the answer is:
never-say-die
'being indomitable' is the definition.
('never-say-die' can be a synonym of 'indomitable')
'i deserve any break' is the wordplay.
'break' indicates an anagram.
'i'+'deserve'+'any'='ideserveany'
'ideserveany' with letters rearranged gives 'NEVER-SAY-DIE'.
(Other definitions for never-say-die that I've seen before include "Refuse to give up" , "Persevere!" , "Don't give up" .)