Series of deliveries managed but took too long (7)
I believe the answer is:
overran
'took too long' is the definition.
(I've seen this before)
'series of deliveries managed' is the wordplay.
'series of deliveries' becomes 'over' (I can't justify this - if you can you should give a lot more credence to this answer).
'managed' becomes 'ran' (both can mean organised or was in charge of).
'over'+'ran'='OVERRAN'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for overran that I've seen before include "Went past an end time" , "overwhelmed the enemy" , "Went on beyond the time limit" , "Went on too long" , "Lasted too long" .)