Give way concerning fast time (6)
I believe the answer is:
relent
'give way' is the definition.
(I've seen this in another clue)
'concerning fast time' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'fast time' becomes 'lent' (Lent is a time for fasting).
're'+'lent'='RELENT'
(Other definitions for relent that I've seen before include "Abandon cruel treatment" , "Become more compassionate" , "Change one's mind" , "Be less strict" , "'Give in, soften (6)'" .)