Think deeply about time-consuming referee (8)
I believe the answer is:
meditate
'think deeply' is the definition.
(I've seen this before)
'time-consuming referee' is the wordplay.
'time' becomes 't' (abbreviation).
'consuming' means one lot of letters goes inside another (consume can mean to bring in or absorb).
'referee' becomes 'mediate' (I've seen this before).
't' inserted into 'mediate' is 'MEDITATE'.
'about' acts as a link.
(Other definitions for meditate that I've seen before include "Ruminate" , "Spend time in thought" , "Think deeply and quietly" , "Ponder" , "Think contemplatively" .)