Be inactive, as old vein's opening in heart (8)
'be inactive' is the definition.
(to tick over is to run at a low level of activity)
'old vein's opening in heart' is the wordplay.
'opening' says to take the initial letters.
'in' is an insertion indicator.
'heart' becomes 'ticker' (synonyms).
The first letters of 'old veins' is 'ov'.
'ov' put into 'ticker' is 'TICK OVER'.
'as' is the link.
(Other definitions for tick over that I've seen before include "(Of engine) idle" , "Run smoothly (or very slowly?)" , "(Of engine) run slowly in neutral" , "Just keep going like idling engine" .)
'be inactive' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'old vein's opening in heart' is the wordplay.
'opening' indicates taking the first letters.
'in' indicates putting letters inside.
'heart' becomes 'ticker' (synonyms).
The first letters of 'old vein' is 'ov'.
'ov' put within 'ticker' is 'TICKOVER'.
'as' is the link.
Can you help me to learn more?