Unfortunately Maya isn’t one to depend on (8)
I believe the answer is:
mainstay
'one to depend on' is the definition.
(I know this)
'unfortunately maya isn't' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'maya'+'isnt'='mayaisnt'
'mayaisnt' anagrammed gives 'MAINSTAY'.
(Other definitions for mainstay that I've seen before include "Rope to the mast is the chief support" , "Strongest support" , "Pillar of strength" , "Chief source of support" , "Bulwark" .)