Some toast a blessing for fast (6)
I believe the answer is:
stable
'fast' is the definition.
(fast can mean secure)
'some toast a blessing' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'STABLE' can be found hidden inside 'toast a blessing'.
'for' acts as a link.
(Other definitions for stable that I've seen before include "'Firmly fixed, not moving (6)'" , "Standing firm" , "setting for the Nativity" , "Unchanging (condition); some racehorses" , "Place of birth" .)