Plainly apparent in extra time (5)
I believe the answer is:
overt
'plainly apparent' is the definition.
(I've seen this before)
'extra time' is the wordplay.
'extra' becomes 'over'.
'time' becomes 't'.
'over'+'t'='OVERT'
'in' is the link.
(Other definitions for overt that I've seen before include "Open, not 1 across" , "Open and obvious" , "Conspicuous" , "Plain to see - manifest" , "Plainly apparent" .)