Kind son gripped by aversion to speed (4,5)
I believe the answer is:
make haste
'speed' is the definition.
(I've seen this before)
'kind son gripped by aversion' is the wordplay.
'kind' becomes 'make' (make is a kind of kind).
'son' becomes 's'.
'gripped by' means one lot of letters goes inside another.
'aversion' becomes 'hate' (I have seen 'Strong aversion ' mean 'hate' so perhaps 'aversion' could also mean 'hate').
's' put within 'hate' is 'haste'.
'make'+'haste'='MAKE HASTE'
'to' is the link.
(Other definitions for make haste that I've seen before include "Hurry, don't be slow" , "speed" , "Shake mate to hurry up" , "Festina lente - . . . . . . . . . slowly" .)