Problems created by hot reactions (7)
I believe the answer is:
hitches
'problems' is the definition.
(I know this)
'by hot reactions' is the wordplay.
'by' is a charade indicator (letters next to each other).
'hot' becomes 'h' (abbreviation eg on taps).
'reactions' becomes 'itches' (allergic reactions).
'h' next to 'itches' is 'HITCHES'.
'created' is the link.
(Other definitions for hitches that I've seen before include "Snags, temporary stoppages" , "Temporary problems or stoppages" .)