Stop to deliver outside of zone (6)
I believe the answer is:
freeze
'stop' is the definition.
(I've seen this before)
'deliver outside of zone' is the wordplay.
'deliver' becomes 'free' (I've seen this before).
'outside of' means to remove the middle letters.
'zone' with its middle taken out is 'ze'.
'free'+'ze'='FREEZE'
'to' is the link.
(Other definitions for freeze that I've seen before include "Harden into ice" , "Stand still!" , "Become motionless with fear" , "Solidify with cold" , "Suspend" .)