Truck on run, one from which all our deliveries come? (5)
I believe the answer is:
uteri
'from which all our deliveries come?' is the definition.
(plural of uterus - as in delivering a baby)
'truck on run one' is the wordplay.
'truck' becomes 'ute' (Australian abbreviation for utility vehicle).
'on' says to put letters next to each other.
'run' becomes 'r' (cricket abbreviation).
'one' becomes 'i' (Roman numeral).
'ute'+'r'+'i'='UTERI'
(Other definitions for uteri that I've seen before include "organs, in hospital patients" , "Places seeing early growth" , "Wombs" , "Organs reproducing" , "baby carriers" .)