Very good time in mine (3)
I believe the answer is:
pit
'mine' is the definition.
(down the pit)
'very good time' is the wordplay.
'very good' becomes 'pi' (I've seen this in other clues**).
'time' becomes 't'.
'pi'+'t'='PIT'
'in' is the link.
(Other definitions for pit that I've seen before include "Cavity" , "Place for the accompanying orchestra" , "Hollow" , "Tip into hole" , "Stop to refuel" .)