Tense before start of game, Kelvin escapes reprimand (4,3)
I believe the answer is:
tick off
'reprimand' is the definition.
(I've seen this before)
'tense before start of game kelvin escapes' is the wordplay.
'tense' becomes 't' (abbreviation used in many dictionaries).
'before' is a charade indicator (letters next to each other).
'start of game' becomes 'kickoff' (beginning of a football match).
'kelvin' becomes 'k' (abbreviation for the unit of temperature).
'escapes' is a deletion indicator.
'kickoff' with 'k' taken out is 'ickoff'.
't'+'ickoff'='TICK OFF'
(Other definitions for tick off that I've seen before include "Rebuke" , "Mark items individually" , "carpet" , "Mark as present; reprove" , "Reprimand (someone)" .)