Footwear affected in training regime (4,4)
I believe the answer is:
boot camp
'training regime' is the definition.
(camp where military cadets are trained)
'footwear affected' is the wordplay.
'footwear' becomes 'boot' (boot is a kind of footwear).
'affected' becomes 'camp' (camp can mean exaggerated or affected).
'boot'+'camp'='BOOT CAMP'
'in' acts as a link.
(Other definitions for boot camp that I've seen before include "where terrier potentially goes" , "Centre for juvenile offenders" , "US training centre for military recruits" , "Scene of strict discipline for young offenders" , "correctional facility" .)