Equal time and distance (6)
I believe the answer is:
parsec
'distance' is the definition.
(I've seen this before)
'equal time' is the wordplay.
'equal' becomes 'par'.
'time' becomes 'sec' (**).
'par'+'sec'='PARSEC'
'and' is the link.
(Other definitions for parsec that I've seen before include "Unit for measurement of distance of stars" , "fair distance" , "Unit of astronomical length" , "Immense unit of distance" , "Enormous distance" .)