Old boy's attacks without heart blockages (9)
I believe the answer is:
obstacles
'heart blockages' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'old boy's attacks without' is the wordplay.
I cannot quite see how this works, but
'old' could be 'o' (abbreviation as in OT - Old Testament) and 'o' is present in the answer.
'boy's' could be 'bs' (abbreviation used in schools) and 'bs' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for obstacles that I've seen before include "barriers" , "Obstructions, impediments" , "Hindrances, impediments" , "hurdles" , "These block" .)