Time imagined by son provides change of heart (6,8)
I believe the answer is:
second thoughts
'change of heart' is the definition.
(I've seen this before)
'time imagined by son' is the wordplay.
'time' becomes 'second' (unit of time).
'imagined by' becomes 'thought' ('think' can be a synonym of 'imagine'. I am not sure about the 'by' bit.).
'son' becomes 's' (genealogical abbreviation for son).
'second'+'thought'+'s'='SECOND THOUGHTS'
'provides' is the link.
Can you help me to learn more?
(Other definitions for second thoughts that I've seen before include "change of plan" , "change of heart" , "Change of opinion possibly" , "Revised view" , "Doubts; reconsideration" .)