Give way concerning a fast time (6)
I believe the answer is:
relent
'give way' is the definition.
(I've seen this in another clue)
'concerning a fast time' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'a fast time' becomes 'lent' (I've seen this in another clue).
're'+'lent'='RELENT'
(Other definitions for relent that I've seen before include "'Give in, soften (6)'" , "Be merciful" , "Become less severe, soften" , "Relax severity or opposition" , "Become more compassionate" .)