Deliveries agree to change, but too keen (9)
I believe the answer is:
overeager
'too keen' is the definition.
(I've seen this before)
'deliveries agree to change' is the wordplay.
'deliveries' becomes 'over' (I've seen this before).
'to change' indicates an anagram.
'agree' anagrammed gives 'eager'.
'over'+'eager'='OVEREAGER'
'but' acts as a link.
(Other definitions for overeager that I've seen before include "too anxious to please?" , "Excessively keen" , "with enthusiasm" .)