Depended on a fast round (5)
I believe the answer is:
leant
'depended' is the definition.
The answer and definition can be both to do with fundamental existence as well as being past participle verbs.
Perhaps there's a link between them I don't understand?
'a fast round' is the wordplay.
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'round' indicates putting letters inside.
'a' put inside 'lent' is 'LEANT'.
'on' acts as a link.
Can you help me to learn more?
(Other definitions for leant that I've seen before include "Rested sideways (on something)" , "Inclined (towards)" , "pressed on" , "Tipped" , "Slanted" .)