Tolerate everything that hurts! (5)
I believe the answer is:
allow
'tolerate' is the definition.
(I know that tolerate is a kind of allow)
'everything that hurts' is the wordplay.
'everything' becomes 'all' (all things).
'that hurts' becomes 'ow!'.
'all'+'ow'='ALLOW'
(Other definitions for allow that I've seen before include "Permit or agree" , "Admit as acceptable" , "Permit or concede" , "brook" , "Permit or acknowledge" .)