Maintenance at no cost without worries (8)
I believe the answer is:
carefree
'without worries' is the definition.
(I've seen this before)
'maintenance at no cost' is the wordplay.
'maintenance' becomes 'care' (synonyms).
'at no cost' becomes 'free' (I've seen this in another clue).
'care'+'free'='CAREFREE'
(Other definitions for carefree that I've seen before include "Unconstrained" , "Not worried" , "relaxed" , "Light-hearted, no worries" , "Unconcerned - cheerful" .)