Enthusiasm for guy's toy wasted two years (5)
I believe the answer is:
gusto
'enthusiasm' is the definition.
(I know that gusto is a type of enthusiasm)
'for guy's toy wasted two years' is the wordplay.
I cannot really see how this works, but
'for' could be 'to' (eg both can mean 'in the opinion of') and 'to' is present in the answer.
The remaining letters 'gus' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gusto that I've seen before include "ardour" , "Verve, zest" , "Energy" , "Relish - zest" , "Hearty enjoyment" .)