Dill driving well, possibly (5,3)

I believe the answer is:

under par

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This could be a double definition.

'dill driving' is the first definition.
The definition suggests an adjective which matches the answer.

'well possibly' is the second definition.
The definition suggests an adjective which matches the answer.

Can you help me to learn more?

(Other definitions for under par that I've seen before include "Below average - it's good in golf" , "low" , "Not feeling great" , "Out of form" , "doing well 8 [ON COURSE]" .)

I've seen this clue in the Sydney Morning Herald.

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