What's stressful about a resistance producing delay? (8)
I believe the answer is:
tarrying
'delay?' is the definition.
(tarrying is a kind of delay)
'what's stressful about a resistance' is the wordplay.
'what's stressful' becomes 'trying' ('trying' can be a synonym of 'stressful').
'about' is an insertion indicator.
'resistance' becomes 'r' (abbreviation).
'a'+'r'='ar'
'trying' placed around 'ar' is 'TARRYING'.
'producing' is the link.
(Other definitions for tarrying that I've seen before include "Loitering" , "waiting" , "using delaying tactics?" , "Lingering, staying on" .)