Equal to time and distance (6)
I believe the answer is:
parsec
'distance' is the definition.
(I've seen this before)
'equal to time' is the wordplay.
'equal' becomes 'par'.
'to time' becomes 'sec' ().
'par'+'sec'='PARSEC'
'and' acts as a link.
(Other definitions for parsec that I've seen before include "Astronomical length - scrape (anag)" , "three and a quarter twenty sevens [LIGHT YEARS]" , "3.26 light years" , "Unit for measurement of distance of stars" , "Large unit of distance" .)